A & B has jointly booked a shop in a mall.Paid full & final payments to builder.A is 75% & B is 25% partner which is signed by both on letter head of A. Now market price is increased to 3 times. B is insisting to get 50% share in it.otherwise he will not come forward for registration of agreement.Hence possession is also not given by builder.A is ready to register the agreement in joint name of A & B.can builder register & give possession in joint name in the absence of B.