I have uploaded a very early schematic. All the major building blocks are there but a lot of little things still need to be added.

I have gone with JST XH connectors for the Lipo Balance connections. I will need to decide how the output of the regulator gets used for charging the highest cell in each balance connection. If I assume users will never try and plug in more than one battery at a time, everything should be okay. Some protection mechanism might be worth designing.

I will also need to add a some mosfets and resistors to use for discharging and balancing the cells.