Control the TMG traffic

Hi,

Is it possible to restrict only access primary site TMG while secondary site TMG acts as passive?

Here is the configuration,

Primary Site -> 2* TMG in DMZ, 1 * primary EMS in Corp Lan.

Secondary Site -> 2 * TMG in DMZ, 1 * Secondary EMS in Corp Lan.

Primary EMS is replicating to Secondary EMS.

Secondary site is for DR purposes and all TMGs are joining to EMS.

TMG is mainly for Outlook anywhere and OWA access.

Kelvin Teang