picture 3 is the way you would do a cheap active balancer
you dont know if that bms you have is why the pack is out of balance, your cells could be fine and the bms could be your problem
easiest way to bypass the bms would be to run 2 new leads (battery positive/negative) to the controller
you would still use the existing charging port to charge/balance the pack
personally id toss the bms and just plug an active balancer on the old bms plug, like plug and play
