update of similar parts.

SW2006

I've got a driveshaft, PartA, that is in production and fully
dimensioned.
Now I want to make PartB with some drastic changes to one end of the
drive shaft, but keep everything else the same on the opposite end of
the driveshaft. And this may also result in another PartC.

What is the best way to make a change in Part A, so it will also
update parts B,and C? For ex, a small diameter change of Part A, so
the same diameter will change in parts B, C and D?

Do I have to use an Equation to link to part A? Is there anything
else that can be done? Should I also save a copy of Part A to Part B,
and C then add/make changes to B and C. I dont' think I can use a
spread***/design table, b/c parts B and C have some drastic changes
on the one end of the driveshaft.

Also, I would then like to use the drawing from partA with all the
dimensions, and be able to dimension most of part B and C. How can i
do this?

Right now, i just saved partA as PartB and PartC, and now manually
make changes to A, B and C as they are needed, but is a pain in the
***, if I make a change in A, it does not update B and C in the part
and drawing. Also, I really do not want to re-dimension a drawing for
part B and C, when A has most of everything.

How can I be a little more efficient at this?

samurai.
.