You would need to have 2 different relationship or post object fields.
If you’ve changed it to a post object field then you’ll need to figure out how to get the value of the post object field. Also, it’s been some time since I created that and even the method used for getting the value of the relationship field may have changed.
You would need to either duplicated much of the code, especially the JS parts, or you would need to alter the JS to detect what field is being changed and populate the other fields accordingly.
I don’t have a working example of doing this with 2 sets of fields.
