Local BDC and Remote BDC

I wanted to add a BDC to one of my remote site which has about 100 users.

Site A – Central Office
It has 250 users.
It has a PDC (file server) and a BDC (Exchange 5.5 Server).

Site B – Remote site
It connects to site A via frame relay with FT
It has 100 users. Users complained of waiting at least 5 to 10 minutes for the login script & antivirus to complete.
I wanted to add a BDC to this site, so users will get authenticated through this BDC server.
Is it possible?

Help!
Thanks,
-Lake