For those of you who do Not have an automatic transfer switch

[Kevin125 4,772]

Data Centers do this with N+1 generator arrays. I don’t deal with those kinds of systems, but they are likely expensive as hell and way too big for a residential generators.  As I think about it, they probably feed the generators in the very big inverters, which is where the sine wave out is controlled.  3 phase in their case. Also accepts a feed from batteries to maintain power during the generator start process.

This may be a problem requiring too much stuff for a typical house.

It may be easier to break out the panel to be fed by two different generators. One for lights and similar loads plus critical stuff like a fridge.  Then the other larger gen/panel for well pumps, AC units, furnace blowers, etc.