Father returns after 55 years and demands parental care. What to do?

My father had abandon me ( i am the son) and my sister when we were 3-5 years old and was living with his sister with no contact with us at all level. But now my father came back to us after 57 years and demand medical expenses because his sister's family denied him such and left at the streets. Now police is forcing, harassing us and ordering to take medical expenses responsibility(which is alot and we can't afford). Is there any legal responsibility on me to take care of my father? Or my father's sister's family member has legal responsibility as he was living with them for past 57 years? What course of action do i have to avoid police harassment? Whome to approach police station kr court? What do i do?