In exchange, they can gift her the house in their will or a similar arrangement. 

Some loans allow a gift of money, some do not. 

ROI,  means return on investment and does not consider down payment, equity percentage, or if funds used for investment were borrowed, stolen or gifted or traded for equity.

Lastly, as a housewarming gift, Bryan purchased topsoil to grade my property in spite of my indication that I would do this at my own expense.Overall, I am pleased with the quality of the work and the level of communication I've had with this company, and it is a pleasure to have done business with them.

Additionally, if your partner has $0 funds and you have 100% of the funds that would be used to purchase the home, you can use your funds as well and not have to count them as a gift, so long as they are in your account and fully seasoned by the time you buy the property. 

I imagine he would have to be the one qualifying for the loan, and my down payment would count as a gift to him, but I'm not very familiar with how this all works. 

All seemed okay, then they demanded I sign a gift affidavit for the funds.

If that is your first investing purchase have a contingency line item that will help to do the unexpected expense or it might be a gift. 

That is in the range of an allowable “gift”.

The reason he asked was there's a high end, and low end appraisal depending on what you need it for.Now, if it's intra-family, and you're getting it below market, to play it safe, do the sale based on the appraised amount, and have the difference handled as a gift.