Thank you all, Now I understand all three of you guy's comments, @bin extend to the wall is a must if I am treating the vertical "bulkhead" as a wall type, then after defining the location of this wall the ceiling outline needs to be RE-defined to extend into the core of this "bulkhead" wall piece. After this @barthbradley joint too will work to provide a continuous gypsum board line in the section view if the Rules for Layer Joins @martijn_pater is correctly defined in terms of their joining hierarchy.
FOLLOW UP QUESTION
Now that the section is correct, from the ceiling plan I am getting a double line as REVIT is projecting the "thickness" of the gypsum board on the "bulkhead" wall on to the ceiling plan, (see screenshot). So in the ceiling plan the gypsum board is not appearing continuous. Any good method of getting around this apart from making the linework invisible?
Below is ceiling plan on the left, section on the right.
