[nativepaul]

To charge both at the same time and balance the individual cells you would have to charge them up as an 8s1p pack then parallel them into a 4s2p after charging, I don't know the 1210 balancer but if you meant the hyperion LBA10 it is only capable of balancing 6s on its own, you would need 2 LBA10s and a datacable to let them balance up to 12s.

Alternatively you could charge them separately as 4s1p packs on your single balancer, but obviously charging 2 packs separately will take you twice as long as charging them all together as a long string making a 8s1p pack.