What I do, may be wrong to some, but works and others do it is:
Cut (or pull from pins) both power wires from both servo connections but leave the grey signal.
The grey signal wires now get plugged into the wkm
Get a servo extension cable and cut off the male end, leave female end alone. You can leave the grey wire or remove.
Solder both positive from servos together with the positive wire of the extension
Likewise for negative
Solder uBec to main power lead on board
plug female end of cable into male Ubec end and you're good to go
