In East Boston Savings v. Ogan, 428 Mass. 327, 330, 701 N.E.2d 331 (1998), the Supreme Judicial Court (the "SJC") explains the basis for equitable subrogation as follows: The question whether to apply subrogation depends on a balance of the interests of the competing mortgagees because "the right to subrogation rests upon equity." The court guards against the unjust enrichment of either party by granting to the later mortgagee the priority status intended by the parties to that transaction, only so long as the interests of the intervening mortgagee are not prejudiced . Ogan requires that the follow factors be present for equitable subrogation: Before equitable subrogation applies, a court must determine: (1) the subrogee made the payment to protect his or her interest; (2) the subrogee did not act as a volunteer; (3) the subrogee was not primarily liable for the debt paid; (4) the subrogee paid off the entire encumbrance; \(5) subrogation would not work any injustice to the rights of the junior lienholder. (428 Mass. at 330.)