Customer has 2 generators feeding 2 separate ATS/ panels. Customer asking if both ATS could be wires in series to one of the 2 panels but be backup by both generators one as a lead and other as a lag. One generator would back up the other generator if it failed. If the lead generator turns on first the lag generator would have a delay and stay off unless lead generator failed then lag generator would engage. If this could be done is other code compliant? I don't see an issue unless it's something where we are violating code or safety.