When working as a supporting artiste you will always be deemed as self-employed.
However, you may have a standard or enhanced disclosure certificates from another employer for other work that you do. These are more detailed than the basic disclosure certificate but only available via another employer. As they are more detailed we will accept a standard or enhanced DBS in place of a basic DBS. If this applies to you please upload either one of these here: https://documents.castingcollective.net/
If you are registered with the enhanced DBS update service, you can also upload a screenshot showing your subscription details page that show your contact details and update status. This would only apply if you did work via another employer.