THIS. I don't understand from the OP's description what he is trying to do. If nothing else, scribble up a simple hand drawn--scrap of paper "block diagram" and take a photo of it and post it
.......And I agree with others---this may not be a DIY deal.
I installed a genset feed plug into my house panel with one of the approved mechancial lock deals. It's simple. The genset breaker MUST go in a certain position at the top near the main. You shut off the main, and the lockout slides, allowing the genset breaker to be turned on. Then it's a matter of killing whatever breakers in the panel you do NOT want to feed with the genset. For me this includes the 240 breakers for the water heater, and range.
In my case the meter feeds a panel that supplies the garage, and goes from there underground to the house. Yet the house panel is NOT treated (in this case) like a "sub" panel. This is a big difference. With the house "main" pulled for the genset, there is NO connection to the garage or meter.