In the Migrate Users Wizard, when I select the option to 'Prefix all accounts' and 'Migrated associated groups' the group accounts are prefixed as well.
In the Migrate Users Wizard, when I select the option to add a Prefix in the event of a conflict, groups that conflict with an existing group are prefixed as well.
Groups will also receive a prefix because the option to 'Prefix all accounts' is selected. Or, groups that conflict will also receive a prefix if you have selected to prefix users in the event of a conflicting account.
You can Migrate Users and Groups in separate steps if you are planning to prefix all accounts. Do not select the option to migrate associated user groups.
Alternatively, you could use a script to accomplish this.
You would use the Migrate Groups Wizard. Optionally within this wizard, you can select the checkbox to Migrate the members of the groups selected, but do not specify an account prefix in the wizard. You then specify a pre-migration script that would add a prefix only to the users as follows:
Specify this script as a VBScript, specify it as a User Pre-migration script. Change the word 'whateverprefix' to the user prefix that you want to use. Then copy this entire script in the box provided in the Migrate Groups Wizard.
settings.put "CopiedAccount.TargetSam", "whateverprefix" & sourceobject.name
settings.put "CopiedAccount.TargetName", "CN=whateverprefix" & sourceobject.name
This script is provided as an example. It should be tested in your test environment to make sure it is adding the prefix correctly before using in production.
This same script can be used to add a prefix to group accounts only, by specifying it as a Group Pre-migration script.