In Context Parts

I have an assembly that has a "skeleton" sketch with critical
dimensions for a number of parts. The "skeleton" assy sketch covers
several subassy's. My goal is to make it so the skeleton sketch
controls dimensions in parts in the several sub assy's.

When I create parts using "Insert/Component/New Part" from the menu,
and mate each with the main assy. front plane, everything works fine.
I use convert entities to create in context sketches in each part. I
can change the "master" sketch, and all the individual parts change
size.

The problem is that I would like to move groups of these parts from
the main assy to a sub assy, to reduce the complexity of the main
assy.

When I use "Insert/Compenant/Assy from Selected Components" from the
menu, the resulting parts located in the new sub assy are no longer in
context. When I change the "master" sketch, the part sizes don't
change.

Furthermore, it seems imposible to create a subassy sketch that has in
context geometry from the main assy. If I could do that, all would be
easy, as the main assy would have the skeleton sketch for all
subassy's, and the subassy's would just pull in their part of the
skeleton sketch in context. Then the subassy's parts would be
designed in context with the sub-assy.

Sorry, I am new, and am confused.

Any ideas?

Thanks,

Dave