Family rights

Hi. my name is Meera. my husband and i have a joint prooerty. which is located in delhi . we are going US for 2 years officially. now the hows which is in the name of both of us is vacant. my husband wants it to give to his sister but i m not in favor of it. as she is infacted with HIV (AIDS). and her husband has also left her. now she has a son of 14 years if age . they are completely depended on us. we support them finacially as she cant work and is in bed. what rights do i have on my propoerty. how i can make it secure. and can go US freely without any tension. as she is asking to shift in our house. what action i can take. its a family matter so littke sensitive also. this is the case of one sister in law there is one younger sister in law also who is unmarried. she is 25 years old and not able to compkete her nursing for last 4 years. my mother in law and father in law are no more and havent left any property or bank balace. now she is also depended on us we are taking care of her also. support her financially. she lives in PG near her hosputal college. the with her is that she has relationship with many boys. she has oborted babies twice. but still we are supporting her. what category she comes to prostitute or what?? and how much she has right on our property and assets. how we can get relief from both of sisters. plz guide and help