Validity of Status of Occupants

I have a property in Salt Lake, Kolkata, In 1995 I have executed a developer's agreement and a GPA( only notarized) in favor of a developer to develop the same with clauses of developer's allocation, subject to permission from the Govt. of West Bengal and owner's allocation(no permission obtained). Later I found out that the developer had sold off the developer's part in my property to two parties by taking money from them and entering into only MoUs (unregistered) on Rs.10 stamp paper with them and giving them physical possession. I was totally unaware of this activity due to my absence in the city. Developer is now out of the seen. The occupants are now claiming to be owners of their part in the property by virtue of the MoU and making payments to the developer. There is no registered sale/assignment deed in their name nor any tenancy agreement, nor any licensee agreement. I have already filed a suit for eviction before the period of adverse possession. How do I challenge their claim and get them evicted.