Regarding sale deed

We are selling our property and belo cluase have been added by our buyers lawyer. I just need guidance if this if below are valid. We are selling and out title is clear and we dont want any hassle from our buyer later on. My concern on below once we hand over keys why we need to bother. Are the beliw cluases correct ? Below are the clauses. We are vendors The Vendors hereby covenants, agrees and declares that they will Support every lawful application also for changes and mutation before the concerned corporation and other 11.That the Vendors does hereby further agreed to keep the Vendees harmless and indemnified against any loss which the Vendees may be put to or sustain by reasons of any defect in the title of the Vendors or any body else claiming through or under the Vendors. 12.The Vendors further assures and declares that, they shall sign on files and execute such necessary affidavits, whatsoever in nature for getting the mutation of the said schedule property in the Municipal record and other records in the name of the Vendees. 13.The Vendors hereby declare that, they revoke all the promises and testamentary dispositions by them heretofore made, before if they made any in written or oral, concem to the ScheduleProperty 14. The Vendors herein shall sign on necessary papers to perfect the title deed and mutation in the concerned department/offices. 15.Thatthe Vendors hereby further assures to execute any Rectification o r Supplementary Deed required by the Vendees in future regarding the schedule property to make perfect title of the Vendees without demanding any fresh consideration to execute such documents.