Forget the power distribution. It is missing info. You need to look at the diagram for the power windows, which is only found in 82 and older wiring diagrams. With that diagram you should be able to find where the short is.

Fuses a & b are 16 A, but fuse 2, which supplies power to fuses a & b through a relay, is only 8 A. That's why (when there's a short) only fuse 2 blows since it is lower A than fuses a & b.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked