One DC with three sites

Here's an odd one:

In one town, I have three sites (Site1, Site2, Site3). Site 1 has
three T1s: one T1 to Site2, one T1 to Site3, and one T1 to the rest
of the nationwide organization. For this post I'm only concerned with
Site1, Site2, and Site3. All three sites have sites defined in AD and
Site1 has a DC. For some reason the workstations and server in Site2
and Site3 are not authenticated against the DC at Site1 (4ms ping
reply), they are using a DC across the country (80ms ping reply).

To fix this, I'd just delete the AD site entries of Site2 & Site3 and
add their subnets to the site entry for Site1, however we have a DFS
that replicates between the 3 sites and if we consolidated our site
definitions computers at Site2 could refer to the DFS and instead of
getting the local replica, they get the servers at Site3. I am
thinking of just rewriting our login & startup scripts to check the
subnet of the machine and map the local servers. Then using a package
like AllSync or rsync to handle the intersite replication.

Does anyone know of any way around this?

Thanks for your help,