There is an "authmodetranslator" tool that allows you to match the current users (SIDs) from the current AD to the new one so for instance, when reviewing the repo history, Plastic will be able to resolve the old SIDs even if then you are using a new AD (with new SIDs).
You will also need to reconfigure the Plastic server authentication mode to point to the new AD server.
The tool can be downloaded at :
You need to copy the tool in the Plastic "server" folder in order to run it.
As mapping the users one by one is something that will drive you crazy, it's possible to provide a file with the user "translation" matching.
You need to get the users list. A fast way is using the "cm li" command (or directly parsing the "c:\Program Files\PlasticSCM5\server\users.conf" file).
Then you need to get the new values for your user names, this can be done querying your AD server.
The file format is: OldSEID||NewSEID