I don't think so. Unless you buy a business class account. Easiest to just have them make an account and then make your recipes public and they can search them
Yes, with a Premium Plus membership you can form a group, and invite a Premium, Plus, or Pro member to join you. They would have their own account, and be able to access whatever data you want them to see in the group you set up. You can allow editing, deleting, creating, etc with recipes or brew sessions, or limit it to view only. You can keep some things private or not allow editing or creating if you want to as well.
Please let me know if you have any questions about this, or want to see it in a demo.