It's a complicated situation.
Let me start off by saying that I expect that Revit is expressly designed to prevent this kind of thing.
I have a window family with a fire separation butting into the mullion in the middle. It's a beefly mullion in the window family. I now know that I should have made two windows but there are situations where both windows serve the same fire compartment, and I've used the same family. They have the same header on the exterior wall. ie-it's not (terribly) obvious from the exterior that the dwelling unit division is in the middle of the window.
I have about three or four different window families that do this because of sizes, styles, headers, etc.... I'd rather not double my window family count.
I've scheduled the windows in a given fire compartment by adding an instance parameter that I can sort/group by. This is really nice, because I can get a total of the window area in any given fire compartment.
So I've had to give the double window to one if the fire compartments. The one it crosses into is missing half of that window family's area.
I went and set up an IF statement that either report the glazed area, or half of the glazed area, based on an integer switch in the type.
Now what I need to do is trick Revit into reporting that half area twice. Under two separate instance parameter groupings.
This is a tough one to explain. Is it coming across at all?
I have a window
it sits across the junction of fire compartment 1 and fire compartment 2
Half of it's area reports to FC1, because I gave the family an instance parameter to sort by.
I'd like to trick Revit into reporting this half area again, but sorted by FC2, so it totals in a schedule correctly for each fire compartment.