Associating multiple FreeForm entries with a single Craft entry
I was thinking about this myself, and I found the following 2 articles which I have been going over. It looks like it is quite possible:
http://craftsnippets.com/articles/using-template-hooks-in-craft-cms
https://docs.solspace.com/craft/freeform/v3/overview/relations.html#overview
The 2nd link has a heading for “Relating more than one element” which looks like it would apply in your situation.