Hi there @magiclevinho,
To expand on what @MattJohnson_PG says.....from the assembly, you can Edit [or Create] in-Place, then use the "Inter-Part Copy" command to select certain reference surfaces to pull into the new PAR/PSM file, then use these for 'Replace Face" [or profile geometry location] up to the reference set selected.
Attached ST9 file set, is a very crude assembly [ZIP compressed file] I made, using that technique,....for your interrogation. HTH.
Design Manager Streetscape Limited
Solid Edge ST10 [MP0] Classic [x2 seats]