I'm looking to 'sync' (maybe not the best term) users from multiple Azure AD instances into one single instance.
Reasoning behind this is the following: our company is part of a 'group' together with a few other companies. Each company is self supporting in the sense that they have their own administration, tenants (some are using Google instead of Azure) and so forth.
Now for a couple of things it would be handy to have one AD instance with all of the company employees combined. What we're currently looking into for instance is a provider for physical access to our office building. They offer the ability to link into Azure AD, but only for a single tenant at a time. So I can use it with one company only, which is not very useful in our case.
I looked into B2B options which at first I thought would be the solution for this. I created a new AD tenant. Now although it's perfectly possible to 'invite' users from the other tenants, this is a manual process which needs to be repeated for every new user. I was hoping there would be a way to 'link' the two ADs and set-up grants like "all users from tenant X are members of group Y" in order to be able to use those groups for the access solution mentioned.
The annoying thing is that when searching for 'sync', I mostly find things that are related to syncing on-prem users using AD Connect. So maybe I'm searching in the wrong place. Can anyone elaborate whether this scenario is supported somehow?