diff --git a/extensions/wikidata/module/langs/translation-en.json b/extensions/wikidata/module/langs/translation-en.json
index a2c6b8191..50be8999a 100644
--- a/extensions/wikidata/module/langs/translation-en.json
+++ b/extensions/wikidata/module/langs/translation-en.json
@@ -23,6 +23,9 @@
     "wikidata-schema/add-statement": "add statement",
     "wikidata-schema/add-value": "add value",
     "wikidata-schema/add-qualifier": "add qualifier",
+    "wikidata-schema/copy-reference": "copy",
+    "wikidata-schema/paste-reference": "paste reference",
+    "wikidata-schema/reference-copied": "copied",
     "wikidata-schema/add-reference": "add reference",
     "wikidata-schema/add-reference-snak": "add",
     "wikidata-schema/property-placeholder": "property",
@@ -146,4 +149,4 @@
     "warnings-messages/no-unit-provided/body": "Values such as <span class=\"wb-issue-preformat\">{example_value}</span> on {example_item_entity} are expected to have units.",
     "warnings-messages/invalid-entity-type/title": "{property_entity} used on items",
     "warnings-messages/invalid-entity-type/body": "Uses of {property_entity} on items such as {example_entity} are invalid."
-}
\ No newline at end of file
+}
diff --git a/extensions/wikidata/module/langs/translation-fr.json b/extensions/wikidata/module/langs/translation-fr.json
index 0280f78fe..2924caee2 100644
--- a/extensions/wikidata/module/langs/translation-fr.json
+++ b/extensions/wikidata/module/langs/translation-fr.json
@@ -20,6 +20,9 @@
     "wikidata-schema/add-statement": "ajouter une déclaration",
     "wikidata-schema/add-value": "ajouter une valeur",
     "wikidata-schema/add-qualifier": "ajouter un qualificatif",
+    "wikidata-schema/copy-reference": "copier",
+    "wikidata-schema/paste-reference": "coller une référence",
+    "wikidata-schema/reference-copied": "copiée",
     "wikidata-schema/add-reference": "ajouter une référence",
     "wikidata-schema/add-reference-snak": "ajouter",
     "wikidata-schema/property-placeholder": "propriété",
@@ -139,4 +142,4 @@
     "warnings-messages/no-unit-provided/body": "Des valeurs telles que <span class=\"wb-issue-preformat\">{example_value}</span> sur {example_item_entity} devraient avoir des unités.",
     "warnings-messages/invalid-entity-type/title": "{property_entity} utilisée sur des éléments",
     "warnings-messages/invalid-entity-type/body": "Les utilisations de {property_entity} sur des éléments tels que {example_entity} sont invalides."
-}
\ No newline at end of file
+}
diff --git a/extensions/wikidata/module/scripts/dialogs/schema-alignment-dialog.js b/extensions/wikidata/module/scripts/dialogs/schema-alignment-dialog.js
index f9a1ebc8b..cc3770773 100644
--- a/extensions/wikidata/module/scripts/dialogs/schema-alignment-dialog.js
+++ b/extensions/wikidata/module/scripts/dialogs/schema-alignment-dialog.js
@@ -244,12 +244,18 @@ SchemaAlignmentDialog._reset = function(schema) {
   if (!this._schema.itemDocuments.length) {
     // this._addItem();
   }
+
+  this._copiedReference = null;
 };
 
 SchemaAlignmentDialog._save = function(onDone) {
   var self = this;
   var schema = this.getJSON();
 
+  if (schema === null) {
+    alert($.i18n('wikidata-schema/incomplete-schema-could-not-be-saved'));
+  }
+
   Refine.postProcess(
     "wikidata",
     "save-wikibase-schema",
@@ -394,17 +400,32 @@ SchemaAlignmentDialog._addItem = function(json) {
 
 SchemaAlignmentDialog._itemToJSON = function (item) {
     var statementGroupLst = new Array();
-    item.find('.wbs-statement-group').each(function () {
-        statementGroupLst.push(SchemaAlignmentDialog._statementGroupToJSON($(this)));
+    var statementsDom = item.find('.wbs-statement-group');
+    statementsDom.each(function () {
+        var statementGroupJSON = SchemaAlignmentDialog._statementGroupToJSON($(this));
+        if (statementGroupJSON !== null) {
+          statementGroupLst.push(statementGroupJSON);
+        }
     });
     var nameDescLst = new Array();
-    item.find('.wbs-namedesc').each(function () {
-        nameDescLst.push(SchemaAlignmentDialog._nameDescToJSON($(this)));
+    var nameDescsDom = item.find('.wbs-namedesc');
+    nameDescsDom.each(function () {
+        var nameDescJSON = SchemaAlignmentDialog._nameDescToJSON($(this));
+        if (nameDescJSON !== null) {
+           nameDescLst.push(nameDescJSON);
+        }
     });
     var inputContainer = item.find(".wbs-item-input").first();
-    return {subject: SchemaAlignmentDialog._inputContainerToJSON(inputContainer),
+    var subjectJSON = SchemaAlignmentDialog._inputContainerToJSON(inputContainer);
+    if (subjectJSON !== null &&
+        statementGroupLst.length === statementsDom.length &&
+        nameDescLst.length === nameDescsDom.length) {
+      return {subject: subjectJSON,
             statementGroups: statementGroupLst,
             nameDescs: nameDescLst}; 
+    } else {
+      return null;
+    }
 };
 
 /**************************
@@ -513,12 +534,21 @@ SchemaAlignmentDialog._addStatementGroup = function(item, json) {
 
 SchemaAlignmentDialog._statementGroupToJSON = function (statementGroup) {
     var lst = new Array();
-    statementGroup.find('.wbs-statement-container').first().children('.wbs-statement').each(function () {
-    lst.push(SchemaAlignmentDialog._statementToJSON($(this)));
+    var domStatements = statementGroup.find('.wbs-statement-container').first().children('.wbs-statement');
+    domStatements.each(function () {
+       var statementJSON = SchemaAlignmentDialog._statementToJSON($(this));
+       if (statementJSON !== null) {
+          lst.push(statementJSON);
+       } 
     });
     var inputContainer = statementGroup.find(".wbs-prop-input").first();
-    return {property: SchemaAlignmentDialog._inputContainerToJSON(inputContainer),
-            statements: lst};
+    var propertyJSON = SchemaAlignmentDialog._inputContainerToJSON(inputContainer);
+    if (propertyJSON !== null && domStatements.length === lst.length && lst.length > 0) {
+       return {property: propertyJSON,
+              statements: lst};
+    } else {
+       return null;
+    }
 };
 
 /**************
@@ -593,6 +623,28 @@ SchemaAlignmentDialog._addStatement = function(container, datatype, json) {
         e.preventDefault();
     }).appendTo(toolbar3);
     SchemaAlignmentDialog._plusButton($.i18n('wikidata-schema/add-reference'), addReferenceButton);
+
+    var pasteToolbar = $('<div></div>').addClass('wbs-toolbar').appendTo(referencesToggleContainer);
+    var referencePaste = $('<span></span>')
+        .addClass('wbs-paste-reference')
+        .appendTo(pasteToolbar)
+        .hide();
+    var pasteIcon = $('<span></span>').addClass('wbs-icon').appendTo(referencePaste);
+    var referencePasteButton = $('<a></a>')
+        .addClass('wbs-paste-reference-button')
+        .text($.i18n('wikidata-schema/paste-reference'))
+        .appendTo(referencePaste)
+        .click(function(e) {
+        if (SchemaAlignmentDialog._copiedReference !== null) {
+           SchemaAlignmentDialog._addReference(referenceContainer, SchemaAlignmentDialog._copiedReference); 
+           SchemaAlignmentDialog._updateReferencesNumber(referenceContainer);
+           referencePaste.hide();
+           SchemaAlignmentDialog._hasChanged();
+        }
+        e.preventDefault();
+        e.stopPropagation();
+    });
+
     if (references) {
         for (var i = 0; i != references.length; i++) {
           SchemaAlignmentDialog._addReference(referenceContainer, references[i]);
@@ -607,17 +659,32 @@ SchemaAlignmentDialog._statementToJSON = function (statement) {
     var inputContainer = statement.find(".wbs-target-input").first();
     var qualifiersList = new Array();
     var referencesList = new Array();
-    statement.find('.wbs-qualifier-container').first().children().each(function () {
-        qualifiersList.push(SchemaAlignmentDialog._qualifierToJSON($(this)));
+    var qualifiersDom = statement.find('.wbs-qualifier-container').first().children();
+    qualifiersDom.each(function () {
+        var qualifierJSON = SchemaAlignmentDialog._qualifierToJSON($(this));
+        if (qualifierJSON !== null) {
+           qualifiersList.push(qualifierJSON);
+        }
     });
-    statement.find('.wbs-reference-container').first().children().each(function () {
-        referencesList.push(SchemaAlignmentDialog._referenceToJSON($(this)));
+    var referencesDom = statement.find('.wbs-reference-container').first().children();
+    referencesDom.each(function () {
+        var referenceJSON = SchemaAlignmentDialog._referenceToJSON($(this));
+        if (referenceJSON !== null) {
+          referencesList.push(referenceJSON);
+        }
     });
-    return {
-        value:SchemaAlignmentDialog._inputContainerToJSON(inputContainer),
+    var valueJSON = SchemaAlignmentDialog._inputContainerToJSON(inputContainer);
+    if (referencesList.length === referencesDom.length &&
+        qualifiersList.length === qualifiersDom.length &&
+        valueJSON !== null) {
+      return {
+        value: valueJSON,
         qualifiers: qualifiersList,
         references: referencesList,
-    };
+      };
+    } else {
+      return null;
+    }
 };
 
 /**************
@@ -655,10 +722,16 @@ SchemaAlignmentDialog._addQualifier = function(container, json) {
 SchemaAlignmentDialog._qualifierToJSON = function(elem) {
   var prop = elem.find(".wbs-prop-input").first();
   var target = elem.find(".wbs-target-input").first();
-  return {
-      prop: SchemaAlignmentDialog._inputContainerToJSON(prop),
-      value: SchemaAlignmentDialog._inputContainerToJSON(target),
-  };
+  var propJSON = SchemaAlignmentDialog._inputContainerToJSON(prop);
+  var valueJSON = SchemaAlignmentDialog._inputContainerToJSON(target);
+  if (propJSON !== null && valueJSON !== null) {
+    return {
+        prop: propJSON,
+        value: valueJSON,
+    };
+  } else {
+    return null;
+  }
 }
 
 /**************
@@ -673,6 +746,20 @@ SchemaAlignmentDialog._addReference = function(container, json) {
 
   var reference = $('<div></div>').addClass('wbs-reference').appendTo(container);
   var referenceHeader = $('<div></div>').addClass('wbs-reference-header').appendTo(reference);
+  var referenceCopy = $('<span></span>').addClass('wbs-copy-reference').appendTo(referenceHeader);
+  var referenceCopyIcon = $('<span></span>').addClass('wbs-icon').appendTo(referenceCopy);
+  var copyButton = $('<span></span>')
+        .addClass('wbs-copy-reference-button')
+        .text($.i18n('wikidata-schema/copy-reference'))
+        .appendTo(referenceCopy)
+        .click(function(e) {
+     if (SchemaAlignmentDialog._copyReference(reference)) {
+       $(this).text($.i18n('wikidata-schema/reference-copied'))
+              .parent().addClass('wbs-copied-reference');
+       container.parent().parent().find('.wbs-paste-reference').hide();
+     }
+     e.preventDefault();
+  });
   var toolbarRef = $('<div></div>').addClass('wbs-toolbar').appendTo(referenceHeader);
   SchemaAlignmentDialog._makeDeleteButton().click(function(e) {
      reference.remove();
@@ -703,9 +790,16 @@ SchemaAlignmentDialog._referenceToJSON = function(reference) {
   var snaks = reference.find('.wbs-qualifier-container').first().children();
   var snaksList = new Array();
   snaks.each(function () {
-      snaksList.push(SchemaAlignmentDialog._qualifierToJSON($(this)));
+      var qualifier = SchemaAlignmentDialog._qualifierToJSON($(this));
+      if (qualifier !== null) {
+         snaksList.push(qualifier);
+      }
   });
-  return {snaks:snaksList};
+  if (snaksList.length === snaks.length) {
+      return {snaks:snaksList};
+  } else {
+      return null;
+  }
 }
 
 SchemaAlignmentDialog._updateReferencesNumber = function(container) {
@@ -715,6 +809,22 @@ SchemaAlignmentDialog._updateReferencesNumber = function(container) {
   a.html(childrenCount+$.i18n('wikidata-schema/nb-references'));
 }
 
+SchemaAlignmentDialog._copyReference = function(reference) {
+   // mark any other copied reference as not copied
+   $('.wbs-copy-reference-button')
+        .text($.i18n('wikidata-schema/copy-reference'));
+   $('.wbs-copy-reference')
+        .removeClass('wbs-copied-reference');
+   var copiedReference = SchemaAlignmentDialog._referenceToJSON(reference);
+   if (copiedReference !== null) {
+      SchemaAlignmentDialog._copiedReference = copiedReference;
+      $('.wbs-paste-reference').show();
+      return true;
+   } else {
+      return false;
+   }
+}
+
 /************************
  * FIELD INITIALIZATION *
  ************************/
@@ -1076,7 +1186,7 @@ SchemaAlignmentDialog.setupStringInputValidation = function(input, regex) {
 
 SchemaAlignmentDialog._inputContainerToJSON = function (inputContainer) {
     var data = inputContainer.data();
-    if (data) {
+    if (data && 'jsonValue' in data) {
        return data.jsonValue;
     } else {
        return null;
@@ -1095,13 +1205,21 @@ SchemaAlignmentDialog._removeStatement = function(statement) {
 
 SchemaAlignmentDialog.getJSON = function() {
   var list = new Array();
-  $('#schema-alignment-statements-container .wbs-item').each(function () {
-     list.push(SchemaAlignmentDialog._itemToJSON($(this)));
+  var itemsDom = $('#schema-alignment-statements-container .wbs-item');
+  itemsDom.each(function () {
+     var itemJSON = SchemaAlignmentDialog._itemToJSON($(this));
+     if (itemJSON !== null) {
+        list.push(itemJSON);
+     }
   });
-  return {
+  if (list.length === itemsDom.length) {
+    return {
         'itemDocuments': list,
         'wikibasePrefix': this._wikibasePrefix,
-  };
+    };
+  } else {
+    return null;
+  }
 };
 
 SchemaAlignmentDialog._hasChanged = function() {
@@ -1130,6 +1248,10 @@ SchemaAlignmentDialog.preview = function() {
   this.issueSpinner.show();
   this.previewSpinner.show();
   var schema = this.getJSON();
+  if (schema === null) {
+    $('.invalid-schema-warning').show();
+    return;
+  }
   $.post(
     "command/wikidata/preview-wikibase-schema?" + $.param({ project: theProject.id }),
     { schema: JSON.stringify(schema), engine: JSON.stringify(ui.browsingEngine.getJSON()) },
diff --git a/extensions/wikidata/module/styles/dialogs/schema-alignment-dialog.css b/extensions/wikidata/module/styles/dialogs/schema-alignment-dialog.css
index 03561fede..2ae8fa79d 100644
--- a/extensions/wikidata/module/styles/dialogs/schema-alignment-dialog.css
+++ b/extensions/wikidata/module/styles/dialogs/schema-alignment-dialog.css
@@ -143,6 +143,7 @@
     opacity: 0.7;
 }
 
+
 .wbs-remove .wbs-icon {
     background-image:linear-gradient(transparent,transparent),url("data:image/svg+xml,%3Csvg%20xmlns=%22http://www.w3.org/2000/svg%22%20width=%2224%22%20height=%2224%22%20viewBox=%220%200%2024%2024%22%3E%20%3Cg%20id=%22remove%22%3E%20%3Cpath%20id=%22trash-can%22%20d=%22M12%2010h-1v6h1v-6zm-2%200H9v6h1v-6zm4%200h-1v6h1v-6zm0-4V5H9v1H6v3h1v7.966l1%201.03v-.073V18h6.984l.016-.018v.015l1-1.03V9h1V6h-3zm1%2011H8V9h7v8zm1-9H7V7h9v1z%22/%3E%20%3C/g%3E%20%3C/svg%3E");
 }
@@ -211,7 +212,8 @@
 
 .wbs-remove,
 .wbs-add-item, .wbs-add-statement-group, .wbs-add-statement,
-.wbs-add-qualifier, .wbs-add-reference, .wbs-add-namedesc {
+.wbs-add-qualifier, .wbs-add-reference, .wbs-add-namedesc,
+.wbs-copy-reference-button, .wbs-paste-reference-button {
     color: #0645ad !important;
     font-size: 0.9em;
     cursor: pointer;
@@ -250,6 +252,10 @@
     color: gray;
 }
 
+.schema-alignment-dialog-preview .wbs-prop-input {
+    float: left;
+}
+
 .schema-alignment-dialog-preview .wbs-qualifier .wbs-statement-container {
     display: table-cell;
     vertical-align: bottom;
@@ -303,7 +309,7 @@
 
 .wbs-qualifier, .wbs-reference {
     position: relative;
-    overflow-x: hidden;
+    overflow: hidden;
 }
 
 .wbs-qualifier .wbs-right {
@@ -318,14 +324,50 @@
 }
 
 .wbs-references-toggle {
-    width: 12em;
     margin: 5px;
+    margin-right: 0px;
 }
 
 .wbs-references-toggle a {
     color: #0645ad !important;
 }
 
+.wbs-copy-reference {
+    float: left;
+    padding: 2px;
+}
+
+.wbs-copied-reference {
+   opacity: 0.6;
+}
+
+.wbs-copied-reference .wbs-copy-reference-button {
+    color: black !important;
+    cursor: default;
+}
+
+.wbs-copied-reference span:hover {
+    text-decoration: none;
+}
+
+.wbs-paste-reference .wbs-icon,
+.wbs-copy-reference .wbs-icon {
+   height: 13px;
+   width: 13px;
+   background-size: 13px 13px;
+   opacity: 0.6;
+   margin-right: 2px;
+}
+
+/* source: Font Awesome by Dave Gandy. https://commons.wikimedia.org/wiki/File:Paste_font_awesome.svg */
+.wbs-paste-reference .wbs-icon {
+   background-image: url("data:image/svg+xml,%3C%3Fxml version='1.0' encoding='UTF-8'%3F%3E%3Csvg version='1.1' viewBox='0 -256 1900 1900' xmlns='http://www.w3.org/2000/svg' xmlns:cc='http://creativecommons.org/ns%23' xmlns:dc='http://purl.org/dc/elements/1.1/' xmlns:rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns%23'%3E%3Cmetadata%3E%3Crdf:RDF%3E%3Ccc:Work rdf:about=''%3E%3Cdc:format%3Eimage/svg+xml%3C/dc:format%3E%3Cdc:type rdf:resource='http://purl.org/dc/dcmitype/StillImage'/%3E%3C/cc:Work%3E%3C/rdf:RDF%3E%3C/metadata%3E%3Cg transform='matrix(1 0 0 -1 53.153 1325.1)'%3E%3Cpath d='m768-128h896v640h-416q-40 0-68 28t-28 68v416h-384v-1152zm256 1440v64q0 13-9.5 22.5t-22.5 9.5h-704q-13 0-22.5-9.5t-9.5-22.5v-64q0-13 9.5-22.5t22.5-9.5h704q13 0 22.5 9.5t9.5 22.5zm256-672h299l-299 299v-299zm512-128v-672q0-40-28-68t-68-28h-960q-40 0-68 28t-28 68v160h-544q-40 0-68 28t-28 68v1344q0 40 28 68t68 28h1088q40 0 68-28t28-68v-328q21-13 36-28l408-408q28-28 48-76t20-88z' fill='currentColor'/%3E%3C/g%3E%3C/svg%3E%0A");
+}
+
+/* source: Font Awesome by Dave Gandy. https://commons.wikimedia.org/wiki/File:Copy_font_awesome.svg */
+.wbs-copy-reference .wbs-icon {
+  background-image: url("data:image/svg+xml,%3C%3Fxml version='1.0' encoding='UTF-8'%3F%3E%3Csvg version='1.1' viewBox='0 -256 1850 1850' xmlns='http://www.w3.org/2000/svg' xmlns:cc='http://creativecommons.org/ns%23' xmlns:dc='http://purl.org/dc/elements/1.1/' xmlns:rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns%23'%3E%3Cmetadata%3E%3Crdf:RDF%3E%3Ccc:Work rdf:about=''%3E%3Cdc:format%3Eimage/svg+xml%3C/dc:format%3E%3Cdc:type rdf:resource='http://purl.org/dc/dcmitype/StillImage'/%3E%3C/cc:Work%3E%3C/rdf:RDF%3E%3C/metadata%3E%3Cg transform='matrix(1 0 0 -1 37.966 1305.5)'%3E%3Cpath d='m1696 1152q40 0 68-28t28-68v-1216q0-40-28-68t-68-28h-960q-40 0-68 28t-28 68v288h-544q-40 0-68 28t-28 68v672q0 40 20 88t48 76l408 408q28 28 76 48t88 20h416q40 0 68-28t28-68v-328q68 40 128 40h416zm-544-213-299-299h299v299zm-640 384-299-299h299v299zm196-647 316 316v416h-384v-416q0-40-28-68t-68-28h-416v-640h512v256q0 40 20 88t48 76zm956-804v1152h-384v-416q0-40-28-68t-68-28h-416v-640h896z' fill='currentColor'/%3E%3C/g%3E%3C/svg%3E");
+}
 
 .wbs-references-toggle .triangle-icon {
     background: transparent url(data:image/svg+xml,%3C%3Fxml%20version%3D%221.0%22%20encoding%3D%22UTF-8%22%20standalone%3D%22no%22%3F%3E%0A%3Csvg%0A%20%20%20xmlns%3Adc%3D%22http%3A//purl.org/dc/elements/1.1/%22%0A%20%20%20xmlns%3Acc%3D%22http%3A//creativecommons.org/ns%23%22%0A%20%20%20xmlns%3Ardf%3D%22http%3A//www.w3.org/1999/02/22-rdf-syntax-ns%23%22%0A%20%20%20xmlns%3Asvg%3D%22http%3A//www.w3.org/2000/svg%22%0A%20%20%20xmlns%3D%22http%3A//www.w3.org/2000/svg%22%0A%20%20%20id%3D%22svg8%22%0A%20%20%20version%3D%221.1%22%0A%20%20%20viewBox%3D%220%200%202.6458332%202.6458332%22%0A%20%20%20height%3D%2210%22%0A%20%20%20width%3D%2210%22%3E%0A%20%20%3Cdefs%0A%20%20%20%20%20id%3D%22defs2%22%20/%3E%0A%20%20%3Cmetadata%0A%20%20%20%20%20id%3D%22metadata5%22%3E%0A%20%20%20%20%3Crdf%3ARDF%3E%0A%20%20%20%20%20%20%3Ccc%3AWork%0A%20%20%20%20%20%20%20%20%20rdf%3Aabout%3D%22%22%3E%0A%20%20%20%20%20%20%20%20%3Cdc%3Aformat%3Eimage/svg+xml%3C/dc%3Aformat%3E%0A%20%20%20%20%20%20%20%20%3Cdc%3Atype%0A%20%20%20%20%20%20%20%20%20%20%20rdf%3Aresource%3D%22http%3A//purl.org/dc/dcmitype/StillImage%22%20/%3E%0A%20%20%20%20%20%20%20%20%3Cdc%3Atitle%3E%3C/dc%3Atitle%3E%0A%20%20%20%20%20%20%3C/cc%3AWork%3E%0A%20%20%20%20%3C/rdf%3ARDF%3E%0A%20%20%3C/metadata%3E%0A%20%20%3Cg%0A%20%20%20%20%20transform%3D%22translate%280%2C-294.35416%29%22%0A%20%20%20%20%20id%3D%22layer1%22%3E%0A%20%20%20%20%3Cpath%0A%20%20%20%20%20%20%20id%3D%22path12%22%0A%20%20%20%20%20%20%20d%3D%22m%200.21601809%2C294.5035%202.28763941%2C1.14744%20-2.29850705%2C1.20871%20z%22%0A%20%20%20%20%20%20%20style%3D%22fill%3A%23645eea%3Bfill-opacity%3A1%3Bfill-rule%3Aevenodd%3Bstroke%3A%23645eea%3Bstroke-width%3A0.06161711px%3Bstroke-linecap%3Abutt%3Bstroke-linejoin%3Amiter%3Bstroke-opacity%3A1%22%20/%3E%0A%20%20%3C/g%3E%0A%3C/svg%3E%0A) no-repeat center center;