Under contract for duplexes and owner can't find leases

[Cheri Malinski]

Good morning.  I'm under contract to purchase two duplexes and the current owner says they are not able to find all of the written leases.  One tenant told me they had been there 5 years and another told me they had been there four.  I have not met the other two.  Everyone is on a month to month lease.  Yes, I understand I should have viewed the leases before going under contract.  I'm just wondering what to do now.  I can use an estoppel agreement but what else should I do?  Thanks for everyone's constructive suggestions.