Maybe. The ONLY way you can do this is if you are living in the home and treating the home as your own. (see below) This means also paying the primary mortgage, taxes, etc. too. This is called having an "equitable" interest in the property.
"Treas. Reg. § 1.163-1(b) permits a deduction for interest paid on a mortgage when a taxpayer is the legal or equitable owner of the property, even though the taxpayer is not directly liable for the mortgage."
A taxpayer becomes the beneficial or equitable owner of mortgaged property (allowing him to deduct mortgage interest on that property) when he assumes the benefits and burdens of ownership. Whether, and when, this has occurred is determined under state law, on a case-by-case basis.
In determining whether the benefits and burdens of ownership have been transferred to a taxpayer, the Tax Court often considers whether the taxpayer (1) has a right to possess the property and enjoy its use, rents, or profits, (2) has a duty to maintain the property, (3) is responsible for insuring the property, (4) bears the property's risk of loss, (5) is obligated to pay the property's taxes, assessments, or charges, (6) has the right to improve the property without the owner's consent, and (7) has the right to obtain legal title at any time by paying the balance of the purchase price. "