Creating a All staff group that includes All staff from another domain

[Lava_za1430]

We manage two domains.

And for the one domain we have a dynamic group that automatically adds members and removes members from the ALL group.

But now the company wants both domains to get the same mail sent to this dynamic group. (vice versa not needed.)

Is something like this possible, because it seems trivial where to even start. 

[#2]

Are both domains in the same Office 365 tenant? If so, add the other domain to the dynamic group query, or remove the domain condition altogether from it. You can share the current query if you want a specific example.

[#3]

No they're each residing in as their own tenant

[#4 · Accepted solution]

In that case, you'll have to add them as contacts/mail users in your tenant first, and vice versa. And probably have a process in place to keep things sync. Or, go the easy route and just send the message to two separate addresses instead. If that's too big of an issue for management, you can create a new DG with both addresses, the "external" one will need a matching contact entry though.

Mail flow rule with the "add recipients" condition is another possibility.

[#5]

I appreciate the help.
Recon the best method here would be to just include both addresses instead.

Once again, thank you for the insight