B2B SPO: GCCH tenant members as guests on commercial Entra

Yes, you can definitely do this. We do this. GCC High is our primary tenant and we have a Commercial tenant to work with our parent company and some partners on proposals. We just make sure we do not share any CUI which is done through DLP. One of the things we have had to do is invite our GCC High users as guests to the commercial tenant. We have set it to automatically accept the invitations. We have not attempted to do any provisioning of syncing of the users between the two tenants as we only have a small group of users who are supposed to use the commercial tenant. This also helps a ton with licensing because they can open office files in their office client without having to have a license for a different account. The process is 100x smoother than have a commercial account and a GCC High account and switching back and forth. The biggest problem I have is users in GCCH wanting features that are not available yet, but they saw them on the commercial side and want to know when they are going to get it.