Agreement Clause

Based on the below mentioned clause, the developer/purchaser can forcefully ask me to vacate the house to " execute or start the deed registration process". And payment will be done on the date of registration. ( I told him that that execution or registration process and registration all happens in one day at registrar office. So do it same day but he is refusing with these 2 points mentioned in the agreement). The builder/purchaser is asking us to vacate to start the registration process. ( Stating these 2 points mentioned in the unregistered agreement) why will i vacate before if everything can be done in same day ? Can i contest ? Now he is saying that he will not start registration without vacant possession. If i appoint a lawyer can i contest legally ? 1.Be it mentioned that the owners is in position on the Ground floor of the below schedule mentioned and it is sole responsible of the owners/vendors to vacate the same and liable to handed over complete vacate possession to the Developer / Purchaser and thereafter Purchaser will conduct the Registration works.. 2.The Purchaser / Developer will pay balance amount of Rs... only on the date of Registration of the said Property.