An active tutor's status cannot be changed from Active to any other status without completing him from any pairs or groups he is assigned to. Since workshops with the type 'New Tutor Training' make updates to the tutor's status (Registered, Graduated, Additional Training Required), there is not a way to enroll an Active tutor in a New Tutor Training Workshop.

If an active tutor is attending a tutor training, there are a couple of options for registering him in a workshop:

1.  Dissolve any pairs he is assigned to and update him to Inactive in any groups.  When he is no longer assigned to any pairs or groups, his overall status will update to On Hold and you will be able to enroll him in a workshop with the type 'New Tutor Training.'  Once he has met the requirements and been completed from the workshop, his overall status will update to Graduated and you can then re-activate his pairs and update him to Active in his groups.

2.  Create a new workshop with a Workshop Type that is not 'New Tutor Training.'  Only New Tutor Training workshops make updates to the tutor's overall status, which mean that tutors who have an overall status of Active can be enrolled in any other workshop type without an issue.  If you go this route, the tutor will not have a line of Tutor History that shows the 'Graduated' status, but you will have the workshop record of his completion.