diff --git a/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.js b/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.js
index f56d85d893..80ccd11c75 100644
--- a/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.js
+++ b/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.js
@@ -188,15 +188,21 @@
      * accounts if necessary.
      *
      * @param {Boolean} isCancel true if the action is a cancel.
+     * @param {Object} opt_accountIdsTransferred map of account IDs that must
+     *     not be removed, because they have been readded in another state.
      */
-    _purgeReviewersPendingRemove: function(isCancel) {
+    _purgeReviewersPendingRemove: function(isCancel,
+        opt_accountIdsTransferred) {
       var reviewerArr;
+      var keep = opt_accountIdsTransferred || {};
       for (var type in this._reviewersPendingRemove) {
         if (this._reviewersPendingRemove.hasOwnProperty(type)) {
           if (!isCancel) {
             reviewerArr = this._reviewersPendingRemove[type];
             for (var i = 0; i < reviewerArr.length; i++) {
-              this._removeAccount(reviewerArr[i], type);
+              if (!keep[reviewerArr[i]._account_id]) {
+                this._removeAccount(reviewerArr[i], type);
+              }
             }
           }
           this._reviewersPendingRemove[type] = [];
@@ -271,9 +277,18 @@
         obj.message = this.draft;
       }
 
-      obj.reviewers = this.$.reviewers.additions().map(this._mapReviewer);
+      var accountAdditions = {};
+      obj.reviewers = this.$.reviewers.additions().map(function(reviewer) {
+        if (reviewer.account) {
+          accountAdditions[reviewer.account._account_id] = true;
+        }
+        return this._mapReviewer(reviewer);
+      }.bind(this));
       if (this.serverConfig.note_db_enabled) {
         this.$$('#ccs').additions().forEach(function(reviewer) {
+          if (reviewer.account) {
+            accountAdditions[reviewer.account._account_id] = true;
+          }
           reviewer = this._mapReviewer(reviewer);
           reviewer.state = 'CC';
           obj.reviewers.push(reviewer);
@@ -290,6 +305,7 @@
         this.disabled = false;
         this.draft = '';
         this.fire('send', null, {bubbles: false});
+        return accountAdditions;
       }.bind(this)).catch(function(err) {
         this.disabled = false;
         throw err;
@@ -509,8 +525,8 @@
 
     _sendTapHandler: function(e) {
       e.preventDefault();
-      this.send().then(function() {
-        this._purgeReviewersPendingRemove();
+      this.send().then(function(keep) {
+        this._purgeReviewersPendingRemove(false, keep);
       }.bind(this));
     },
 
diff --git a/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog_test.html b/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog_test.html
index f7058bd1d7..7adc4a3974 100644
--- a/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog_test.html
+++ b/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog_test.html
@@ -558,5 +558,68 @@ limitations under the License.
         done();
       });
     });
+
+    test('migrate reviewers between states', function(done) {
+      element.serverConfig = {note_db_enabled: true};
+      element._reviewersPendingRemove = {
+        CC: [],
+        REVIEWER: [],
+      };
+      flushAsynchronousOperations();
+      var reviewers = element.$.reviewers;
+      var ccs = element.$$('#ccs');
+      var reviewer1 = makeAccount();
+      var reviewer2 = makeAccount();
+      var cc1 = makeAccount();
+      var cc2 = makeAccount();
+      element._reviewers = [reviewer1, reviewer2];
+      element._ccs = [cc1, cc2];
+
+      var mutations = [];
+
+      var saveReviewStub = sandbox.stub(element, '_saveReview',
+          function(review) {
+        mutations.push.apply(mutations, review.reviewers);
+        return Promise.resolve({ok: true});
+      });
+
+      var removeAccountStub = sandbox.stub(element, '_removeAccount',
+          function(account, type) {
+        mutations.push({state: 'REMOVED', account: account});
+        return Promise.resolve();
+      });
+
+      // Remove and add to other field.
+      reviewers.fire('remove', {account: reviewer1});
+      ccs.$.entry.fire('add', {value: {account: reviewer1}});
+      ccs.fire('remove', {account: cc1});
+      reviewers.$.entry.fire('add', {value: {account: cc1}});
+
+      // Add to other field without removing from former field.
+      // (Currently not possible in UI, but this is a good consistency check).
+      reviewers.$.entry.fire('add', {value: {account: cc2}});
+      ccs.$.entry.fire('add', {value: {account: reviewer2}});
+      var mapReviewer = function(reviewer, opt_state) {
+        var result = {reviewer: reviewer._account_id, confirmed: undefined};
+        if (opt_state) {
+          result.state = opt_state;
+        }
+        return result;
+      };
+
+      // Send and purge and verify moves without deletions.
+      element.send()
+          .then(element._purgeReviewersPendingRemove.bind(element))
+          .then(function() {
+        assert.deepEqual(
+            mutations, [
+                mapReviewer(cc1),
+                mapReviewer(cc2),
+                mapReviewer(reviewer1, 'CC'),
+                mapReviewer(reviewer2, 'CC'),
+            ]);
+        done();
+      });
+    });
   });
 </script>