You certainly can make the adapter you want, the balance board is just a pass-through for different cell-count packs.

If you examine the board, you should be able to follow the traces, and figure out which leads from the balance plug go to which bullet plugs. I'm *almost* positive that, holding the plug with the wires facing you... the far right is the negative, next is the center 2mm plug, next is the positive, and the other wires are not used.