Gen and shore power

I've done it a few times in my coach. I've started the generator while on shore power and I've plugged in while on generator. Of course the first time I tried it was at the dealer's lot with their guidance while taking possession of the coach. I figured if I fried it, at least the dealer would fix it.

Now that I know nothing bad happens, I wouldn't hesitate to start the generator or plug in at any time in any combination.