I am new to FIM, I have deployed FIM for Microsoft Online by first enabling Metaverse Rules Extension MSONLINE.MVExt.dll. Everything synchronizing without problems.

Now I am supposed to create an Exchange forest trust with a company we purchased. We have VPN connection with the two forests and configured AD forest trust. So can I use the same FIM by enabling Metaverse Rules Extension GALSync.dll to use for Exchange contacts sync.

That is it.  You can use FIM to synchronize many sources\targets. 

That is great, thanks for the quick reply.

I have already the enabled the Microsoft Online Metaverse Rules Extension MSONLINE.MVExt.dll but now when I enable Metaverse Rules Extension GALSync.dll now I cannot synchronize Microsoft Online services, how can I use both of them