Is An Agreement Paper acceptable in the court??...

I am a tenant of commercial shop. 2001 we Made An agreement with the landlord to change the tenant name from one brother to another of the same joint family with witnesses signatures. But the name wasn't transferred. In 2006 The Landlord Filed A Case To Evacuate us. Our Lawyer Didn't put the agreement paper in our case. As a result we lost the case. We appealed that all the witnessses passed away during the case. Now Our Lawyer Wants To Show The Agreement Paper In the court, While in The mean Time the landlord passed away. Will the agreement paper be acceptable by the court?