We normally would do this with equations but the way we want to do is too complex for solidworks so every time it crashes the Solidworks. That's why we want to do all the equations in DT.

Basically, we want to make the DT in the assembly and suppress or unsuppress  the boss-extrude1 in the part. If it's an equation, I would do like, "Boss-Extrude1@part1.sldprt" but I couldn't do something like this in DT