i have a formal LR that I need to turn into a BR. The opening is 7'10" high X 8'6. I was planning double doors into the room, will I have to add more wall to fit doors or can I fill that area with doors and frame?
That would mostly depend on the size doors that you can purchase.
One solution would be to install bi-fold doors. That would give you 2 24" doors on each side that would fold outward to frame.
If you don't find bi-fold doors appealing then I would go with 2 36" doors and build in wall accordingly.
Hope this was helpful