Specific relief suit -Subsequent Agreement holder

a) Is it absolutely necessary to make a subsequent agreement holder pendente lite a party in specific relief case? b) If not made a party, will the decree be still binding on subsequent purchaser / subsequent agreement holder pendente lite? c) The subsequent agreement holder (since made a defendant in my case) is actually developer and has stated in his WS that he has sold a few plots in the suit land to some persons. Do I need to bring these persons, if WS to be believed, on record? Appreciate your considered opinion/advise along with citations that I may look up. Thanks & Regards.