Purchase of property

This is not an issue and take all precautions that the money was invested out of father's earnings, and kept in undivided son's name as succession arrangement.  If he wishes to sell the property, his father or guardian has to sign in addition to the minor seller and specifically declare that the amount is needed for family necessities and maintenance.  After attaining the majority, he can sell the property but he can not claim exclusive right, but he is having a trustee relationship with other legal heirs of the undivided family.  Please get the sale deed drafted by an expert advocate and take care of your and your wife's interest during your lifetime.