Situational awareness with GUP and Subnets

Hello,

         I have a SEPM on the east coast of the U.S. and a GUP that will be setup in Europe.  All the European offices will point to the GUP for their delta package updates.  What I am trying to do is setup situational awareness so if an employee in the U.S. flies to Europe and plugs into a an office over there, they are not going over the WAN for their definition updates and will point to the local GUP in Europe.  I'd like to do the same for European employees that fly to the states, so that they point to the SEPM while they are here.

I was wondering if there is anyone that can recomend the best way to go about doing this, keeping inline with Symantec's recomended "best practices"?  Any advice/insight would be appreciated.