Property Title confirmation

I am planning to buy a plot in Indirapuram Ghaziabad. GDA allotted plot. Initially this plot was purchased by 3 partners. one of the partners died and other 2 partners created "waris nama" from deputy magistrate for his wife and 2 sons. The mutation of this property was done in the revenue records in the name of 2 partners and wife along 2 sons of deceased partner. Later one partner purchased his portion from other partner via registered sale deed and then purchased another portion from deceased partners wife and 2 sons via registered sale deed. Now we have all the chain documents complete including: 1. Waris Nama 2. Death Certificate 3. Registered sale deed ( wife and 2 sons) 4. Mutation - 2 partners and wife and 2 sons of deceased partner. My questions is - can we go ahead and purchase this plot , do we have all the title documents clear ? Waris nama says - its not valid for more than Rs,5000 and not valid for property transfer. I checked with few lawyers in Ghaziabad and some said this is good to go and some said court letter or succession letter is needed which is not a easy tasks to get Please help me what should I do and what all documents should I have from owner ? Thank You.