hi neutron ovo hacker: Recently I am working on neutron OVO blue print, and found there are some blocking (slow progress) issues when tring to add new object to Neutron. When I try to add Flavor related object on , I need to add 2 foreign_keys to FlavorServiceProfileBinding : flavor_id: Flavor.id service_profile_id: ServiceProfile.id For ServiceProfile and Flavor object, FlavorServiceProfileBinding is a synthetic_fields, we refer FlavorServiceProfileBinding in , but in currently object base implementation, we only allow synthetic_fields to only have 1 foreignkeys. can anyone help to clarify this? or give some guide on how to overcome ? If there's anyone who working on to fix it too? P. S There are other use case for multiple foreign keys  https://review.openstack.org/#/c/306685/6/neutron/db/flavor/models.py@45 https://github.com/openstack/neutron/blob/184.108.40.206b2/neutron/db/flavors_db.py#L86 https://github.com/openstack/neutron/blob/220.127.116.11b2/neutron/objects/base.py#L429-L430 https://review.openstack.org/#/c/307964/20/neutron/objects/router.py@33 -- Best Regards, Eli Qiao (乔立勇), Intel OTC.