Wiring 24v batteries in parallel with external bms, shunt, and bus. Need help.

[C Subleski]

Can I get some advise on wiring a 2nd 24v battery, in parallel, to my current 24v system. Both batteries the same. Both have external bms's. I'm not sure about negative side of the wiring. The shunt and negative bus bar confuse me. I think I need a negative to the bus....but from which battery? I've attached a sketch of my current system and how I think I need to wire the 2nd battery. Thanks for your help.