OCIS add group member command line?

Is there a way to add a group member from the command line in OCIS? The ocis tool doesn’t appear to have the add-member functionality that we had in OC10: occ group:add-member --member bob admin

We need to make an OIDC user an admin but can’t get into the original admin account to do so via the WebUI.

Bump - any potential solution to this?