I manage this problem like this:
# If the two walls 3&4 have the same BM, I'd only duplicate the BM with different (name & cut fill) while keeping priority and all settings the same.
# If the two walls 3&4 have different BM I'd only check that they've the same priority as they already have different cut fills.
Then I split the vertical wall 3 exactly at the reference line of the horizontal wall.
so that's the result.
AC 25 INT 3002
AMD Ryzen 7 5800H with Radeon Graphics 3.20 GHz 16.0 GB