Everyone would benefit by limiting errors.

I have had several cases where in attempting to add a relationship to a student record, accidentally selected the student as his/her own relation, in a different role (e.g. Parent, Grandparent). There should be some mechanism that keeps this from happening as it has an effect elsewhere in the "oNs" For example if you try to attach a school form to a group that contains a student with dual roles such as described, the form will not save, but won't give you a error, either.