Change database users of service providers

Hello,
Appointments+ seems an awesome plugin :slight_smile:
But I have a problem. In Service Providers, the dropdown users lists, shows all users registered at the WordPress page...
When i have 300 users, all will be shown????
It's possible to change which users as listed? I.e., only lists administrators or collaborators?
Thanks a lot!! It will be helpful for me! :slight_smile: