Forum Discussion
AAD Connect - Object matching across forests, post-installation
Hey Keith,
Not sure I can answer all of your questions, but hopefully I can help the conversation along some.
https://docs.microsoft.com/en-us/azure/active-directory/connect/active-directory-aadconnect-topologies
That link goes over all the supported topologies. The good news is what you are describing is in there in two different forms (all under the multiple forest match users settings). As long as your users only have one active account (which your description points out) this should work.
The bad news is that it seems to match pre-defined the attributes for you to use as either Mail or ObjectSid/an exchangeSid.
I would read into those topologies more, and with that as a starting point I am sure you can get more details, or perhaps someone smarter than me to help you here! :)
Finally yes, you want to re-install AADC as your are changing your topology and design, not modifying your existing one.
Adam