enh: keep allow_blank=False for MANYTOONE that are required
enh: keep allow_blank=False for MANYTOONE that are required

flask-admin/flask-admin,flask-admin/flask-admin,flask-admin/flask-admin,flask-admin/flask-admin,jmagnusson/flask-admin,rochacbruno/flask-admin,jmagnusson/flask-admin,rochacbruno/flask-admin,rochacbruno/flask-admin,jmagnusson/flask-admin,jmagnusson/flask-admin,rochacbruno/flask-admin