With the Lynx NG BMS and batteries you strictly speaking do not need the SmartShunt / BMV on the batteries as the Lynx BMS has a shunt built in. The Cerbo will force DVCC on when connected to the Lynx, however, you can leave the WS500 DVCC off. In your case I would suggest taking your SmartShunt / BMV and setting it to a DC energy meter and swapping it to either measure your additional charger so the Cerbo knows about this or measure the DC system that the Cerbo does not know about.
The WS500 needs an alternator shunt for DVCC to work. Otherwise it only produces the power generated in the alternator which could be useful info. You only need the shunt body which is cheap, the WS500 has all the electronics in. I bought one of these for my WS500 install.