But as I understand the purchaser is under obligation to look into the facts of the sale and as to whether seller is having bonafide rights to sell entire property. In many cases, the purchaser will also be impleaded in the suit. Most of the times the purchasers are not innocent and they wanted to encash the opportunity and grab the property for a nominal amount. (I know many purchasers that purchase such litigation properties, give an undertaking that they will sort out the matter in courts with their expenses, pose as innocent buyers before the court and pull all strings to defeat the real claimants with their political and monetary powers)
Unless the property is divided in meets and bounds and shared legally, no coparcensor can sell entire property and it amounts to fraud also. The limitation for fraud commences from the date of knowledge.
It is always prudent to discuss with local advocates to study the document and how the seller explained of his rights and how he acquired the property.