AZure B2B should be separate from the main idea and they should be Gal separated as well
Azure B2B should be separate from the main AD
and they should be Gal separated as well
it's recommended to not put external user and corporate user in the same repository for security reason (1) wrong right assignment could happen and it would be also easier to delegate to user for SharePoint for example . I though it was already on the roadmap because many complained about guest user able to see all the other guest user and not only the one on his group .
Ypersiel Jean-pol commented
also thing about the licensing model maybe there could be more than 5 times the number of B2B partners