charge batteries in parallel at 3.7 V and discharge in series at 11.1 V
You can't connect them at the same time for charging in parallel and discharging in series.

You can connect them with relays, to either charge in parallel, or discharge in series. 

But it's generally just not worth it. The cost and power consumption of relays would be better spent on simply being able to balance charge a series set of cells.