iwatch cellular does not work in India if paired as family setup watch

I paired iwatch 8 as a family watch for my son. This watch is a cellular watch. I’m unable to setup mobile data on this watch. However, if I pair this same watch as a main watch(not as a family watch) then the cellular option works fine as I’m able to configure mobile data.

So, the problem is specifically under family setup. I tried both the sims, Airtel and Jio and tried pairing with my iPhone 12 and iphone14 pro-max but none of the combinations worked under family setup. I contacted Apple customer care, they tried but couldn’t resolve the issue. Appreciate any help to resolve this issue.