Yes. Sharing Auras in the Aurasma Studio and allowing students or parents to follow your account in-app is undoubtedly the easiest and most efficient way of making Auras available to multiple devices.
However, you can also keep Auras ‘private’ and unavailable to the wider Aurasma platform whilst still making them available to certain app users you have identified. The way to do this is to send your account's private subscription link to the specific email addresses or phone numbers of people you want to be able to see your content.
All you need to do is: click the 'My Account' option (top right) in your account; and then, under your profile image, click the option to 'Share your Private Campaign'. You can then copy the link (using ctrl + c) into an email to be sent to those who you want to be able to view your private AR content. If they tap on this link on a mobile device which has Aurasma installed, the app will automatically open, and they will automatically follow your account containing the Auras you want them to be able to view. This way multiple devices will be able to see Auras in an account which is still private and not available to the wider app user base.