Thanks for the fast reply!:)
That's unfortunate!:/
I wasn't able to find a of-the-shelf board for this purpose, but I read that one can charge them in parallel easier!
So I have drawn another circuit which basically switches the batteries from series to parallel whenever the power source is connected with the help of relais.
The only problem I have is that I will have to switch the Vin's in a specific order to prevent a shortcut, being Vin1, then Vin1, then Vin3 and last Vin2 (Using Capacitors). Is that right?
I also schouldn't have to worry about balancing if I charge them in parallel if I change the charging circuit to charge them with 2C, right?