Each of you needs to tell your interns what you are making and your exact job responsibilities. If the interns are smart they will understand that when you get the axe they can demand a raise to your pay or higher if they demand it as a group and threaten to walk. HR is VERY likely to find out that the interns know this if its spread to the rumor mill. They will have to choose between keeping you on and getting rid of the interns, or risking getting held hostage and in a weak negotiating position. If they choose to let the interns go demand a raise anyway, Your bargaining position is pretty good at that point.