Leases end before property changes hands, seller asking how I would like to handle

[Kelly Skeval]

I am in the middle of purchasing a 4-unit from an acquaintance/friend and it's been a great process; friendly and easy for both of us.  All four of the leases will end shortly before we're able to close and the seller is asking how I would like him to proceed.  I have not had an in depth conversation to learn if anyone is interested in resigning.  My understanding is that this is a good group of tenants who pay their rent and behave.  I've been in their apartments and they're clean.  I know that one apartment is very under rented with a tenant who has been there about 5 years and this landlord has not had the heart to raise the rent. He also told me another one is slightly under rented as well.  All of the apartments can use some TLC and I'll renovate and upgrade as tenants leave so I am able to increase rent.  Although this seller reports all of the tenants pay their rents on time ( and I do believe him) we screen our tenants differently and I tend to be more select so I'm not sure I'd like him to be the one screening and replacing tenants.  

I'm looking for advise on the under rented, long term tenant situation and how to handle the fact that all of the leases are ending.  The seller is easy to work with so I'm sure anything I request he will go along with. Do I allow everyone who is interested in resigning to do so? Should I up their rents slightly?