How do I set values on portfolio purchase

[Jacob Stevenson]

I have an agreement to purchase a portfolio of 8 properties.  One residence was owner occupied.  Three properties still have mortgages on them.  The seller is focused on getting enough money in the first year to pay off their new owner occupied property and second to limit their tax obligation.

This is what I am currently thinking we want to do, but I AM OPEN TO IDEAS!  I purchase three properties with traditional financing to get the seller the cash they need to pay off their new property, from what I understand most banks won't let an owner sell a house with a mortgage on contract, so it seems to be the only option on those properties.  On the other five, I purchase on contract with zero down.  I purchase the formally owner occupied house for as much as possible (how much above appraised value with a bank let me buy a house for?) and adjust the other properties I am purchasing in year one to limit the capital gains of the owner as much as possible.  How much can I adjust prices without any issues?

Thank you for any advice!  First time purchasing a portfolio AND doing owner financing!  Excited to make it happen!