Uneven ceiling and matching moulding heights between 2 rooms Information, help and advice on many architecture, self build and design problems and issues

[Crebourret]

Background info:
Previous owner had a fake dividing wall between dining room and living room.
The next owner then removed part of the fake wall,leaving the ceiling part and side part on one side only.
We, now present owner,decided to remove the remaining fake wall. Only to found out that owner #1 had the dining room replastered (wall) and reboarded (ceiling).

Problem: we managed to fix the problem with uneven wall, but our biggest problem is uneven ceiling between dining room and living room of about 10 mm (9mm board plus1mm plaster); dining room ceiling is plastered and living room is textured paper; we can't match the mouldings heights between the 2 rooms.
Any suggestions?

[welsh brickie]

create a false beam between the 2 rooms, that will hiding the difference