Thanks Charles
I did actually find this page earlier and spent about 2 hours trying to make it work for me. I would get one element sorted and then add another, which would sometimes mess up the first one. When I thought I had it all correct, it then messed up a completely unrelated bounding box that was already in the document that I didn’t need to change, which threw me completely….which is when I asked for help.

Is there any other way to do this other than through a Mapped Content Control process?