This is virtually the same answer I gave to the other, essentially identical, question.
(What you're doing is very nice.)
I can't tell if it is a rental if I don't live in it even though I will not be renting it out.
(This doesn't make sense. No one lives in the place that they rent.)
It's a rental if you rent the house to them -- full blown signed lease, etc. Then gift them the FMV rent.
I am trying to figure out if I can deduct any of the interest/payments.
Not the mortgage interest, since it's not your primary dwelling.
Mortgage interest is any interest you pay on a loan secured by a main home or second home. These loans include:
A mortgage to buy your home
A second mortgage
A line of credit
A home equity loan
If the loan is not a secured debt on your home, it is considered a personal loan, and the interest you pay usually isn't deductible.
Your home mortgage must be secured by your main home or a second home. You can't deduct interest on a mortgage for a third home, a fourth home, etc.
Since you don't live there, you can't deduct the mortgage interest.
OTOH, since it's rental property... congratulations, you're a landlord!
Here are the top ten tax deductions for owners of small residential rental property.
4. Local Travel
5. Long Distance Travel
6. Home Office
7. Employees and Independent Contractors
8. Casualty and Theft Losses
10. Legal and Professional Services
I'd strongly recommend you look at how to turn the rent gift into a charitable donation. It might not be possible, but certainly worth a look. That's probably it's own question: how do I make a deductible charitable contribution to an individual?
Of course, you can just gift the FMV rent to them.
For 2018, the annual exclusion is $15,000.
If the fair market value of rent (since renters don't pay property taxes, repair costs, etc... just rent) is less than
$15000/12 = $1250/month then it falls under the annual exclusion. If FMV rent is over $1250/month, you'll have to -- I think -- file form 709 https://www.irs.gov/pub/irs-pdf/i709.pdf and pay taxes on anything over $15K (or deduct it from your -- as of 2017 -- $5MM lifetime estate exclusion).