I asked this same question and still don't really know how to do this. I think the way to go is to use the first instance as a bookmark, and then use the other fields as cross-references, so then when the first field is filled out, all other fields will be populated identically.

The only problem is that the fields have to be manually updated so it doesn't happen instantly.

Maybe someone else can give a better answer. I'd be interested in hearing it too!