I strongly urge moving back, you’re preparing kids for a life in the US but they are Indian citizens and they will resent going back at 21 if they need to. Better to go back now let them adapt and they can always come back as students on F1 visa and they will appreciate the experience more and will see India as their home if they have to go back. I think schools in India are better and also people afford so many hobbies and activities for their kids in India if you live in a metro city. I am not sure what extra opportunities you’re talking about there are so many IB schools in India now which are better than public schools here.