In Oregon, you do not have to have any relationship at all to your co-borrower.
Gift funds are permitted for FHA loans, as long as they are from immediate family of one of the borrowers. Your partner's father would certainly qualify as immediate family.
There is no "seasoning" requirement for gift funds. But an FHA gift letter is required, which states that the person "gifting" the funds is an immediate family member, and that no repayment of the gitt is ever required. If your loan agent at Wells Fargo was not able to answer this question for you, perhaps you should be looking for someone more qualified to do your loan. This could prove to be just the first of many questions you have, and a lender who cannot answer??? Is that what you want to deal with?
In any event, if you are already committed with Wells Fargo, I wish you all the best.
I hope this helped.
I have been in this business a long time, so I believe you can rely on my answer.
Town & Country Mortgage