Firstly, all the legal heirs of your father would need to obtain letters of administration from testamentary court.
After that, all the children can execute gift or relinquishment deed in favour of your mother to make of her sole owner of the property, which needs to be mandatorily registered after payment of stamp duty.
Your sister can also execute a power of attorney, duly apostilled in favour of any one to do the transfer on her transfer and she would not have to visit India.