When a user registers for membership with a regional federation, he/she will become a member of the regional federation as well as the national federation with membership revenue splits being assigned appropriately to each organization that is involved.
In a multi-level deployment, you can setup document approval rules where approvals must be acquired by both the regional federation as well as the national federation, as an example.
Each organization can have a custom look and feel of the system to make it look like its own separate system even though in the backend all of the data is de-siloed and made conveniently accessible in aggregate form.
Each organization can customize the look-and-feel and the operation of the system in a significant way to make it their own, but still remain part of the connected deployment making coordination with the other organizations significantly easier than it would be with disparate systems at each organization.