@Jared Haxton You are not going to be able to do an owner finance transaction without paying off the existing loan.

Conventional non-owner occupied. 25% down.

For example in many jurisdictions I can STR units in a duplex but cannot STR an ADU (some jurisdictions will let you STR if you owner occupy).

Owners are unloading their STRs due to over saturation in this market.  

They are thier competition and I know the owners.

Mordechai ChaimovitzTwo-unit owner-occupied falls into an odd category, really any 2-4 unit with a nice owner's unit for that matter.

If it’s tied directly to the lender as part of your mortgage agreement, you’d probably need to negotiate with them or refinance with a different lender who doesn’t require that restriction.However, if the restriction is part of the property deed itself and was placed by a previous owner or another party, it can be more complicated.

If it is less than 30 days, the owner can kick someone out for failing to pay or obey the rules.

The #1 reason that landlords fail is due to failure to manage to the lease (Source: American Apartment Owners' Assn). 

Alternatively, your sibling might use a 1031 exchange to defer taxes by reinvesting in like-kind properties, though this doesn't directly fund a primary residence.Other ideas include leveraging a HELOC on the rental properties for the down payment, taking out a 401(k) loan, structuring an owner-financed agreement, or a lease-to-own arrangement.