The black balance wire of the lower Battery goes to the B-, I’m trying to make a system the way that I can unplug the batteries when needed, that’s why I bought JST-XH 3S extension, of which I will use the female sides to connect to batteries and cut off the male sides so I can solder the wires to the plug which goes into the BMS. This can be seen in the diagram.
To be honest, I don’t exactly know if the second black balance wire should be connected or disconnected, but on another persons wiring diagram for two 3s batteries to a 6s BMS I saw the second black balance wire connected.
I don’t exactly know what you mean with the lines “Also charge + typically goes to battery +, in fact all + all get tied together and you put the loop key from batt - to esc -”
Here a link to the female balance connectors I bought: