1)  If the Grandparents have a relationship to their Grandchild(ren) via Relationships,you can inactivate your cloned Grandparent role and should be all set.
2)  If the Grandparents don't have any relationships to Grandchild(ren) via Relationships you can build the relationships via Core or the Contact Card and once that is completed for all Grandparents, then inactivate the cloned Grandparent role.
3)  If your school does not have any relationships to Grandchild(ren), and you can supply a file (including HostIDs or WH UserIDs for the grandchild) which can be used to establish GrandParent-to-Grandchild relationships, then we will send the ticket to the Data Team and they will update the relationships and roles.