With schema v11/v12/v13, OpenStack region id is populated to AAI's cloud region property named "cloud-region-id" which is also part of key to identify a cloud region.
This coupling between OpenStack Region ID and AAI cloud-region-id results constraints to on-board OpenStack VIM instance especially when VID/SO/SDN-C use AAI cloud-region-id only to identify a cloud region.
The proposal is to add one more property to AAI's cloud region's child object "esr-system-info: object" to store the OpenStack Region ID:

esr-system-info: object
openstack-region-id: string ,"OpenStack region ID used by MultiCloud plugin to interact with an OpenStack instance. If this property is not populated with property value, the AAI's cloud-region-id should be populated with OpenStack region ID to maintain backward compatibility"