The BMS switching off due to low voltage should be your last line of defense, not your first. Before your system reaches that point your inverters should have switched off already.
By using the Venus OS large you can use nodered, which enables you to use virtual devices, for example a virtual battery, which can then be fed whatever real information you want. Heres an example of a BMS combiner done in nodered (please note i have not tested the flow myself)