Yes, and you said above they are lottery winners, if they are it is very common to get the green cards (time limit to do that is quick), go back home to finalize everything (it sounds like these people have means and it takes time to effect house and asset sales etc), and then make the “big move” anywhere from 3-11 months later. One absence of that length really isn’t an issue. Been there done that and know a number of other families who have too. They may even have re+entry permits for all we know. There are also dedicated immigration forums full of discussions around these issues.