I have three Exchange Organizations total in our three trusted forests. We use MIIS for Free/Busy replication. Two Forest are in Europe and one in the US. Will the European forests need to rebase?

Q: I have three Exchange Organizations total in our three trusted forests. We use MIIS for Free/Busy replication. Two Forest are in Europe and one in the US. Will the European forests need to rebase?
A: The European forests shouldn't need to rebase unless they are scheduling appointments on behalf of US users or resources. The rebase needs to happen for the mailbox that "owns" the meeting, and then updates are sent to attendees. So, rebasing only needs to happen on mailboxes that create appointments within affected time zones.