I have two AD forest (Forest A and Forest B) with forest trust relation ship and both of them are having their Own Azure AD and O365 Tenants. (A.Com and B.Com). Forest A(A.com) acquired Forest B(B.com) and decided to migrate all mailboxes from O365 tenant of Forest B to Forest A. However in this case they don't want to merge their Active Directory forest, but they want to Migrated users from Forest B O365 tenant to use SMTP of Forest A(A.com) and secondary alias Address of Forest B.com.
Is it possible of Forest B.com to sync the users using AAD connect and set the Primary SMTP address as A.com and alias adresss as B.com? If yes how can this be done ?. Since when we are syncing the users either we need to set the UPN which should be verified in Azure AD , and if i set the UPN of Forest B user as B.com how can his SMTP can be made as A.com?