Apply GC to my father's brother?

[Lsekaran]

Hello,

I am US citizen. I am in the process of applying GC to my parents who are Indian citizens. My father takes care of his mentally hadicapped 67 year old brother in Inida. There is no one to take of him and he cannot handle money or live by himself as he is very ignorant and learning disabled.
Is there a legal method to get my father's brother? Since my parents are getting old, they need help in taking care of him also.

Please advise! I really appreciate your help!

Thanks and Regards,

Latha

PS: Please some one reply if this is not possible at all. Thanks!