I've made  assembly - Polish Air Forces sign:

This logo is built from few parts (body, tail, legs, feathers etc.).

I want make one part (single body) from this assy.

Assy i opened without problem, some operations takes long time, but still works.

I tried to save as part, then in this part combine all bodies. That works, but in result I have HUGE file (approx 200MB part file) and my workstation is too weak to made any next operation. SW still hangs or crash ;-(

Could somebody give me a hint - is possible to turn this assy to one-body part (but still operational in SW)?