No, you cannot make them refinance. No one can make another incur or guaranty debt or encumber their property interest without the other person's consent. You could file a legal action called an action "for partition" to get a court order forcing the sale of the property: that is the law's remedy for when the several owners of property cannot agree as to what to do with it. After the property is sold, the costs of the sale and the mortgage will be paid off, then the remainder divided among the owners. But that is your only option that does not require their consent.