The property in the hands of your vendor was his absolute property.I dont think that the property is ancestral in nature because the vendor's father inherited the property as his share from an oral or unregistered partition from his father's self acquired property, therefore the property which is legally an absolute property of the vendor's father can be disposed by him in any manner as he desires, there is no question for any grievance by the left out child/children (daughters). The suit filed by them is vexatious and has no legal validity for a claim of share as partition or otherwise. If you have been impleaded as a defendant, it is because being a purchaser you have become a necessary party to suit. You can engage an advocate and challenge the issue properly and in support of of your statement you can even produce a back dated legal opinion by an advocate about the status of the property purchased. Do not leave the mater unchallenged in the court, because in Bangalore such land mafias are found menacingly abundant, I am afraid that the vendor may also due to greed of money might have colluded with the so called plaintiff and will abandon the case unattended to become exparte, will compel the other defendants to arrive at compromise situation or negotiable table so that to avoid further tortures and litigation expenses, the other defendants may shell out the money demanded by the plaintiff. This game plan are being notoriously adopted by many in Bangalore for the past many years, do not become a victim to such traps. Your purchase is legitimate, you can fight it till end, you will get justice.