I'm charging multiple LIPOs at the same time and only 1 is connected to the charger with the regular leads - all the others are being charged thru the balance ports. I have been doing so for a long time...
Currently charging 3*1300mAh and 2*2200mAh on 2 chargers
It takes the same time as charging 1 LIPO - just add upp all mAh, set your charger and press GO