I visited Telangana Registration and Stamps Department, Musapet just yesterday. The incharge told me that till date no one has registered here for Play Group. However, if you want to register you can register under Society Act. Institutions like Narayana Engineering and other colleges have register under this Act.
However, under Society Act, only Non-profit / no commercial gain associations only get registered.
We checked with other schools also. Most of them have not registered.
One said they have registered under Society Act.
Below link may be further useful.