If you connect the cells to the balance tap in parallel, the balancer will not see the cells individually. That defeats the purpose of balancing. The heli how-tos on charging two heli lipos at the same time all wire the balance wires in series so the balancer can see and balance each cell. This is a how-to charge and run a pr of 3S1Ps as a 6S2P lipo. Note what he says in the 1st paragraph.

http://www.rbgrn.net/content/46-how-...ks-single-6s1p

It will be complicated trying to get this right and you may never get there. There will be 12 cells involved and I've never seen a balancer that does more than 6cells. If you do any of the connections wrong, you risk all the batts and your charger. The other poss is to charge/balance them separately and then run together. Not the best, but an option.

Just buy a 10th or 8th sized cheap lipo and maintain it. Far less risk that something can go wrong.