[THIN] DSN and Access db

Good Morning,

We have a client running an Aust trade db Application. The application uses a System DSN to talk to an access db.
We require for good governance to run a separate db for each state, does anybody have any ideas as to get round this
problem? Currently if we change the DSN to point to Victoria then all users get the Victoria db and similar for QLD.
I was thinking of changing the DSN on the fly but I am not sure if the application after locating the db would continue using the DSN,
this would cause a corruption with users updating the wrong db. The DSN is hard coded in the the application.

They are running a single 4.5 Adv Citrix server.

Regards

Rob