Purchase of property

Dear Sir. I am planning to purchase a plot. A NRI family of husband. Wife. Two adult children (one married & other single) NRI residing in qatar . Same NRI family wife purchased a plot of 200 sq yards in 2006 & she died in 2013 in gulf and his husband visited India with original plot papers, wife death certificate & had sold the property to a business man in India NRI Husband had not got NOC OR GPA from his NRI Children before Registration of plot so the business man purchaser had insisted for NOC from their NRI Adult childrens from Qatar . so the NRI husband had got NOC / GPA attested by indian embassy Qatar from his NRI Adult children in regard to this 200 sq yards plot property and the NRI husband also had Also given amount received receipt with this GPA / NOC particulars in that on Rs 20/- bond Paper after registration & it is notarized by a advocate to the business man buyer but in registered documents the property is giving the details of NRI husband sold the property to business man by enclosing NRI wife death certificate & above GPA / NOC details their NRI Adult children names are not there in the registered document So now I am interested to purchase this plot from the business man purchaser who purchased from the NRI husband. So how should I proceed. Does anytime in future the NRI Adult children can create problem for this property please let me know. The plot is in business man position & no any hurdles till now.