My dad went to University of Chicago, and he used to interview and admit people in our state. Is this beneficial at all to me? If so, would he need to be my “other recommender” or would that be weird?
Btw our state not Illinois
I don’t think your dad would need to be a recommender - that would be somewhat useless to the admissions committee, as the recommendation would obviously be biased and come from someone with whom you have an unprofessional relationship, unlike a teacher or coach.
That being said, I’m not sure what steps, if any, would need to be taken to make sure the admissions committee knows you have legacy status. You would have stated your legacy status on your common app, and I’m sure it would not be hard for the admissions committee to verify that your father was very active in the alumni community. But of course, I’m sure it wouldn’t hurt to remind the admissions committee - perhaps someone more knowledgeable could comment on the specifics of legacy admittance.
It shouldn’t matter that your state of residence is not Illinois for any purposes whatsoever. 
Thank you for your response @ramboacid