Rerouting without losing connection.

What i am trying to accomplish is to make use of the connection bytes / connection rate function in the firewall to determine users downloading. This works fine. Then i want to move the users to another wan port, by changing their route. However if just changing it, things like emails and so forth get broken. Any ideas on how to gradually mo the users connections to the new rout without braking existing connections? Any suggestions would be appreciated.

If you change the users route anything that requires a persistent connection would disconnect. However I don’t see how you would notice this in web browsing or sending emails. Would affect and online game or a file download or a video buffering.