before understanding Your request in fully detail I can answer that You can create a PMI callout in 3D already to take over into any draft.
But as said before, I have not got it in completeness, so it is hard to give any godd or proper answer.
Awaiting Your images, videos, example files
Please check the image below.
I have made a simple cover as multibody part following your suggestion.
If I can make callout which can pull their part body names automatically with property text like the drawing, it will work for me. But I don't know how to do that.
The stitch line shows here is drawn in draft file. May be I can make a part body at back of cover main part and show as hidden lines in drawing.