Exchange in child forest with users in root forest
I came across a unique situation. Company A is in the middle of the child forest consolidation. Company A has multiple child forests an account forest and a server forest. They are in the process of consolidating into the root forest for a single forest. They are also in the process of a merger. If accounts are created in the root forest for Company B that was acquired, can users be added to Exchange Server in the child forest. Another side. We are considering putting the user accounts in the root forest using azure AD Connect in the child domain to sync them to Office 365. Is it also possible to add the users to local exchange as remote mailboxes in Office 365 if the AD account sits in the root domain?
