Walls and Ceilings - partition wall, butted seams and back blocking

ok, im a first time wall builder. im trying to finish my basement.

my problem is i want to have a partition wall that's flush with the ceiling joists. however i don't know if i should frame the partition wall first and then sheetrock [ceiling first obviously] or do the ceiling first, and then frame the partition wall. either of those options leads me to a problem, and my questions.

can you attach a partition wall where butted seems meet?

if i go the other way, and frame the partition wall first, the sheetrock will be floating between ceiling joists. ive read about "back blocking" but i don't see how you can do that when there's a partition wall involved. any other options other then furring strips? which im against because my ceiling is so low to being with. thanks!

Ok I think your problem is that you will have nothing to attach your drywall lid to right? Do all your framming first! Then your electrical and plumbing. Then hang your drywall. If the space between your ceiling joist and wall is more than 6 inches you need to add backing. Put a 2x4 or a 2x6 flat on top of your top plate of your wall. Make sure it hangs over at least 1 1/2". That will provide backing for your drywall.

yes but the wall is flush against the ceiling joist. so there is going to be a 2ft gap from the last ceiling joist. so the sheetrock ceiling is gonnna hang over by 2ft and not have a place to be attached to because the joist it would be attached to has a partition wall under it.

Ok so turn your 2x on its side and nail (sister) to ceiling joist. Then you will have your 1 1/2 to nail to.