I recommend powerpole connectors and to treat the packs seperately when chargeing. If they are all full at the same time they'll pull down to the lwest capacity cells (4) and then slow down, You should stop imediately.

Another way to do it is to have them all dead, and charge the higher ones only to the same capacity as the lower ones hold. The bigger cells are not full, but they will ALL be more equal "at the empty mark"