@Barryga are you willing to run a couple of tests this morning?
I still want to determine if/how your legacy system and new system are dc connected.
First test: See if the dc lighting goes off when you turn the converter breaker to off.
Second test: is to see if the GFCI outlet trips when you run a small load from it.
Lets not make any changes until we have a better understanding of what is going on.
We should make some tests though.
I hypothesize that the discrete automatic transfer switch has 2 inputs.
1. shore power
2. generator
Please verify that.
I also hypothesize that the ATS output goes to the little mettle junction box and from the junction box it goes to the ac input for each inverter/charger.
Please verify that.