Transfer of Trademark without succession certificate

I acquired a restaurant from its owner few years ago. The trademark remained in the name of the original owner. Due to few other restaurants using a similar name, I resort to contact the owner and change the trademark in my name. But now that the original owner is dead, I reached in sons, who agreed to transfer the trademark to me. But the issue present is they do not have any succession certificate or will, all they have is Legal heirs certificate issued by the Tasildar. Will that be sufficient?