Parallel charging lithium batteries

[WaldPinkler]

I want to increase charge rate of my 12V 270Ah lithium bank.

My inverter unit has a 60A charger. I now have a 1600W generator and want to increase the charge rate when using that.

The charger is a mastervolt mass combi and has a jumper where 2 units can be parallel connected with a master and slave. There is no schematic or much technical info regarding the connection. These units are huge and very expensive ($2k+) so I want to avoid that.

I don't understand the master/slave parallel connection electronically. I believe the manual said a 2nd unit's power should be matched with the other. (they sell higher power models).

What options are there to increase the charging rate?

Can I just connect another battery charger? It seems to work fine with multiple mppt charges working at the same time.