AD on 2nd office

I have a client who has 2 offices. The main office houses the 2 DC with AD. The second office is almost setup and will have a VPN connection to the main office. My question is if there is a connection to Office 1 but I have a 3rd DC with AD with GC enabled would office 2 use the DC there to authenticate users instead of using the VPN to authenticate to DC#1 or 2?

Thanks