Artist Growth only allows for one user login (email address) to be an Owner of an organization. If you have a situation where you need to be the owner of multiple organizations, you will need to use separate email addresses. Artist Growth highly recommends you reach out directly via in app messenger or email support@artistgrowth.com to understand what you are trying to do, as there may be a more effective set up to walk you through.
To access another organization from your user login, you must be invited to that organization from either its owner or one of its admins.