Dear Friend
I like your query.
Let me tell you buying and selling of immovable property in India is governed by the Transfer of Property Act. The said act has not barred Muslims from selling their property. As long as that seller is alive and he is the absolute owner of that property you need not worry. You can buy his property without being worried about his wives or children. You only need to confirm beyond doubts that he is the absolute owner of the property he is selling.
Also, hire a good lawyer to make proper sale deed.
Regards
VIRAJ KADAM
Advocate, Supreme Court of India