control boolean operation

Hello,

at the moment we are using for geometry modeling our own BSP (Binary Space partition) Kernel that work very well. In boolean operation we have complete control about the result surfaces (and edges).
E.g. if we unite two boxes, which are on the same plane and got an equal height we can decide how the top surfaces that may intersect will look like.

E.g we now take the two top Faces of this boxes
1.Box -> Surface A
and
2.Box -> Surface B

both are wihtin the same plane and overlapping

in all Kernels we would get
A Unite B
-> new Face C

But we need
A Unite B
X= B -A
-> org Face A (plus edges) and X (plus edges)

Or
A Unite B
X= A-B
-> org Face B (plus edges) and X (plus edge)

is there any way to control the boolean operation in cascade to create a similar behaviour on the face and edge level for overlapping entities

thank you
Markus Zajc