Supervision during lunch?

We have received calls informing us that principals are planning to have teachers supervise lunch eating with their classes so that older students don’t enter the cohorts, or so that kids are not eating in a common area. According to our collective agreement we have a duty-free lunch break, so teachers are not required to do supervision during that lunch break. HR tells us that they have reminded principals of the need to respect the duty-free lunch in making plans for supervision of students at lunch.  If, because of health protocols, teachers are required to supervise when students are eating their lunches, then it would have to be during instructional time.