Parents objecting son & daughter in law to take their stuffs from their home

The son & daughter in law is moving into a new home because the in-laws are torturing the daughter in law that is why the son decided to move with his wife in a new home. In the marriage the bride's father gave the mentioned stuffs: Furniture includes Bedroom Package, Sofa, Center Table, Dining Table Electronics: Television, Refrigerator, Washing Machine, Microwave, Air Conditioned, Mixer Grinder Home Appliances etc. The parents call their daughter in law while she was celebrating her birthday with her parents and husband and the parents in law said her vacate the flat and take away your stuff or else they will throw. Now when the son went to vacate the flat, the parents are objecting and forcing the son to give in a writing that the son & daughter in law are moving with their own will, also they are forcing the son to write that he has no rights in his father's property otherwise they will not allow the son and daughter in law to take their stuff (what bride's father gave in her marriage) Please advise.