def child_relationship_parent(self, crid, role):
        return self.child_base + crid + "/" + role
https://familysearch.org/developers/docs/api/tree/Child-and-Parents_Relationship_Parent_resource
dataset/ETHPy150Open AmEv7Fam/familysearch-python-sdk-opensource/familysearch/parentsAndChildren.py/ParentsAndChildren.child_relationship_parent