Prestige applies to collections, not to individual user profiles. If you have a Prestige account, anyone you invite to share it will be able to access Prestige features when they are in your collection, even if their own accounts remain at the Aspire level.
You can share a collection with someone by adding them as a Collaborator. While one person (the person in whose account the collection exists) is the primary owner of a given collection, that person can invite as many Collaborators as they like. As long as the primary owner is Prestige, all other Collaborators can remain at the Aspire tier and need not pay for their own Prestige accounts to access Prestige features on the same collection.
To invite collaborators, simply go to the main Home tab on the mobile app and under Collection Management, select the second tile: Manage Collaborators.
Once selected, you can not only see current Collaborators, but you can Invite new Collaborators by selecting the gold Invite button at the bottom right. Once done, you can select from a number of ways to send the invitation to your Collaborator, for instance via text or email. Choose one of the options and a link along with a six-digit code will be sent to them.
Once they tap the link and input the code, they will be able to access your collection. This is accomplished by going to the main Home screen and selecting the downward pointing chevron that is beside your name at the top of the screen. A drop-down list will appear from which you can select the collections to which you have access.
Please note, Collaborators can currently only be added on the mobile app, but users can toggle between collections on both the mobile and web apps.