A supplied roomId property, will make the dialog use that room for the invites, rather than creating a new one

src/components/views/dialogs/ChatInviteDialog.js

@@ -37,6 +37,7 @@ module.exports = React.createClass({
         ]),
         value: React.PropTypes.string,
         placeholder: React.PropTypes.string,
+        roomId: React.PropTypes.string,
         button: React.PropTypes.string,
         focus: React.PropTypes.bool,
         onFinished: React.PropTypes.func.isRequired
@@ -189,6 +190,17 @@ module.exports = React.createClass({
     },
 
     _startChat: function(addr) {
+        if (this.props.roomId) {
+            Invite.inviteToRoom(this.props.roomId, addr).catch(function(err) {
+                var ErrorDialog = sdk.getComponent("dialogs.ErrorDialog");
+                Modal.createDialog(ErrorDialog, {
+                    title: "Failure to invite user",
+                    description: err.toString()
+                });
+                return null;
+            })
+            .done();
+        } else {
             // Start the chat
             createRoom().then(function(roomId) {
                 return Invite.inviteToRoom(roomId, addr);
@@ -202,6 +214,7 @@ module.exports = React.createClass({
                 return null;
             })
             .done();
+        }
 
         // Close - this will happen before the above, as that is async
         this.props.onFinished(true, addr);