If the ceiling was installed first, as it should have been, you may just want to try a simple solution first.
When the ceiling rock is installed before the walls then its supported along the edge by the wall rock. In the area where you have truss uplift use a magnet such as
The Handyguys Podcast Amazon Affiliate Store - BUILDER'S MAGNETIC STUD FINDER
and identify all the screws you may have near the edge. i would then remove any screws or nails you have within 18" of the wall. Patch everything up and then paint.
Worst case is you need to open it up again and do something fancier. Or, did I miss the point of your post?