Based on your description ("She has an account setup already in A.D but with a slightly different shortname."), the easiest way to do this is to simply log in as the AD account to establish cached credentials and the default, empty home folder. Then, log back out of the AD account and into the local admin account (you have a local admin, right). From there, use terminal to rename the home folders and to change ownership of the home folder. Follow this example below.
You have an existing user, Bob Smith, that has a short name bob, stored in NetInfo, and with a home folder of /Users/bob. This user has a UID of > 501.
You have an AD account, Bob Smith, that has a short name bsmith, stored in Active Directory, and using the default AD settings, will create a home folder in /Users/bsmith. This user has an Active Directory GUID.
Based on the above items, have the user log in with bsmith, to force the creation of the /Users/bsmith home folder. The user will now have a local NetInfo account (bob), which contains all of his data and a new account (bsmith), that contains the contents of the User Template.
Log off from the bsmith account and log in as the local system admin. From there open Terminal and do the following:
Move the folders around, first, the new empty folder:
sudo mv /Users/bsmith /Users/bsmith_empty
Next, move the home folder that contains all the user's data to the new home folder path:
sudo mv /Users/bob /Users/bsmith
Note, all commands above are non-destructive. We are NOT deleting anything. Simple moving (renaming) the folders.
Next, you need to change ownership as the folders are still owned by the local user, not the AD user. Use the following example to accomplish:
sudo chown -R bsmith /Users/bsmith
The -R is recursive, meaning that this will apply to the folder and all contents.
That is all. Log off of the admin account and back into the bsmith account. Everything should look exactly the same.
With one exception. Keychain will likely need to be updated. I will guess that the bob account used a different password than the AD bsmith account. You will need to use Keychain Access to update the keychain password or you will be annoyed with requests to unlock it.
If you do not have a dedicated local admin account, this becomes a bit more problematic. Not impossible, but a bit trickier. I will assume you've done the correct sysadmin task and have a dedicated local admin account.
Hope this helps. This is a trivial task. No data move. Can be accomplished in less than 10 minutes.
