Dear Kittu,
Relationship with Lord is a personal matter and not to be discussed with anyone even in family unless no other way left. You must respect your family’s feelings. Baba is not a person but faith and love in our heart. Baba himself used to say, “Be attached to your Guru.”. He exist in all forms. Nothing and No one is beyond him. As concern to disbelief by family, Have Patience and be firm on your faith without performing any ritual publically. Time will change their beliefs. Further Guru Vart is only a way of performing puja, there are other ways also exist. You can adopt other forms of worships like reading Sai Satcharitra, Chanting and listening Baba’s Bhajan, Reading Leelas of Baba etc.
May Baba Bless You to be Firm on your faith and to hold the Patience !
om sri sai ram !