Need to redirect folders but many people are using the same Windows user/login

Small business network ... for safety, I'm wanting to turn on Folder redirection for all workstations.  However, as it turns out - about half of the 12 employees in the business have been using the same windows login for sometime.  i've never seen this done and can't imagine why it  is this way - but now I'm curious what will happen if I implement folder redirection?  my gut tells me it's going to be best to get all users using their own windows login before doing this  - but then what is the simplest way to get the current/local data to their new user account?

Server 2012r2 and Windows 7 Clients.