Problem with lease contract agreement for cell tower

Dear lawyer, Two weeks back we signed a lease agreement with indus towers in our home, that we will be given monthly rental for a lease of 13 years. And the agreement doesn't have a stamp. They promised it will be registed in 90 days but have started installing and almost done already. Now I realised there is an issue with getting an inheritance certificate for my paternal uncle due to missing identity certificate only having death certificate( father elder brother who died but haven't got married). And there a clause that prevents me getting any rent from indus, if I could not register this agreement. iv. The Indemnifier(s) shall in a timely manner fully cooperate and provide all the necessary documents, and present itself along with the proper witnesses (two in numbers) for registration of the Agreement, wherever it is applicable under the law, before the appropriate authority as notified either by the Indemnified or any of its agents, representatives, and on default or failure of any of the above, the Indemnifier(s) agrees that without prejudicially affecting the rights of the Indemnified under the Agreement and / or with respect to the Premises, the Indemnified shall be well within its rights to continue to possess and use the Premises and the Indemnifier(s) shall have no right under the law or under the Agreement to claim rent or any money under whatsoever name or manner till the later of (i) the Agreement is registered, or (ii) the expiry of the rent free period; Pls advise what's my best option now. If indus delays registration citing this reason.