Subtable Implementation

I have a system that has already been implemented/gone live and we’re now doing an expansion to other divisions within our department that has required us to put subtables in for contracts and attachments (I reviewed all of the subtable best practices and tips before we made this decision).
My question is - it appears that if I want to apply a different filter for a linked field in each subtable that I’ll actually have to set up separate linked fields. For example the company linked field on the contract record being filtered by the department on the company record. Is that correct?

Also - for conversion actions, I know they have to be mapped separately in the subtables, but other than remapping them pointing from the subtable to the correct table is there anything I have to do? My conversion actions don’t seem to be working even though I created them from within the subtable and mapped the same fields as were in the top table (ex. for converting from the transitional contract files field), which is how it is discussed on the related wiki pages.