Should i be using iassembly? multiple sub assemblys to have different overall dims

I am pretty new to inventor, and am not sure what is the best way to achive this....

I work for a sheet metal fabricator. I have created an assembly for a fabricated door that consists of two adaptive sheet metal and one adaptive standard part constrained to an overall part (called overall_dims) to make sure the sheet metal parts end up the correct size. The idea being that the dims for the overall part can be amended to suit any door size and the metal parts update automaticly.

This would be fine if I only needed one door at a time, but I would like to create another assembly and add mutliple different sized doors as sub assemblys.

What is the best way for me to do this?

door inner.zip

These are the zipped up files, if they are unziped and added to a project file called iass_adaptive parts_02 it should open i hope, please let me know if I am doing this wrong.

iass_adaptive parts_02.zip

iass_adaptive parts_01.zip

door outer.zip