Muslim League split into Indian and Pakistani sections. The Indian members of the League chose not migrate to Pakistan, formed the Indian Union Muslim League(IUML).
Muhammad Ismail won on Muslim League ticket from Madras Constituency, but he did not become a Pakistani, he chose to be an Indian. It was by choice. He became first president of IUML.
You have to give same choice to non muslim citizens of Kashmir. Either they can stay in muslim majority kashmir or get an independent kashmir for minority. It will be their choice.
Situation of Kashmir is exactly what the situation of India was in 1947.