Property issue

My friend's father has owned three houses in which two are in india and other one is in singapore. His parents and two brothers are singapore citizens . As I has a girl child, they left him in india. However his father was helping his family by sending money from there for many years. Now he is around 80 years old and came back to india for treatment. Now he is unconsious and not written any will statements. But he is orally telling the houses he bought in India and singapore are given to his sons. How I can legally guide with this?. Since his parents are Singaporeans, can he get share in all the three houses? Please advice what should I do? My frined's brother's families are well settled in Singapore.