InfoPath Dev

I have a drop-down in a repeating field that I need to limit to unique choices. The drop-down is populated by a people picker on the same form. http://www.markwheeler.com/img/TRequest.png The repeating section is only available to "admins" where they can assign teleconference numbers to a scheduled request. These numbers also need to have a unique user assigned to them. How can I remove previously selected users from showing up in repeating drop-downs once selected? The people picker is in the Main dataconnection at Attendees > Person > (I am using) DisplayName in the drop-down. The User field in the repeating section is in a Secondary Data Connection (Conference Master). I submit those lines of data via an XML New method to UpdateListItems. I just can't quite figure out the xdXDocument:get-Dom() or preceding-sibling solutions found elsewhere on these forums. When an admin clicks the Assign button, I am writing that repeating data to a second SharePoint list.

I actually got this to work for me. The following expression had to be applied to the pc:Person datafield. not(pc:DisplayName = xdXDocument:getDom("ConferenceMaster")/dfs:myFields/dfs:dataFields/d:SharePointListItem_RW/d:User) The following drop-down box does not actually get filtered until the Assign button is clicked; as shown in the screenshot in my original post.