Refinancing Investment Property as Primary Residence

So my parents have a rental property that they have been renting for the past 10 years, it was their primary residence for 12 years prior to renting. But now my brother and I have moved into the house with some friends from college and are renting it from my parents. They have been looking into refinancing the house and were wondering if they can/how they can refinance it as a primary residence. Their names are on all of the utilities now, been almost a year.

Would they be able to claim it as a primary residence because they have actually family in it? Or do they themselves have to be living in the house?