You can have the seller carry back part of the down payment or bring in a private lender for part of the down payment. 

Partnership agreements carry significant weight unless they violate some sort of public policy or seek to waive a duty case law demands is non waivable.

Owner financing really comes into play on a 5 unit or more because then someone is going to have to carry a commercial loan which is much harder to get. 2-4 families get snatched up quick.

We did not make it inside before she stopped twice to carry on conversations.

The the sellers may have capital gains income from the sale so by recommending they carry back a note with you, they can spread their gain out over a multi-year.

They will carry a higher rate than a conventional loan but they are out there.

Plan is to reach out to my personal network to raise money for the down payment, and aim for a seller carry back on top of a bank loan.

Only recommendation there is to carry umbrella insurance, which you should have regardless.Your banker is correct on all accounts

I'm with @Carrie Hiner.

They all have quirks in their lending committees (typically they carry their own paper) so you want to know if they're a good potential lender for you.