You can add existing admins to a site through the account management page. Simply follow these steps:
- From the Company Dashboard, navigate to Manage > Users
- Search for the admin, using their name or email. (If they don't already have an account, you can click the "add user" button)
- Click the three dots next to their name, and select Add to Site As Admin
- Next to the desired site, click Assign
When the admin next signs in, they will see that site from the site selector page.
Can I remove them from a site?
Yes, simply follow the above steps and click Unassign during step 4