There are many families out there that have separated parents or other family members who would appreciate use of the app for sign in and out rather than "Guest" options.

As it stands at the moment I have to give access to financial information and the ability to change booking days if anyone else would like to use the app.

This doesn't work for separated parents where one parent has the account and pays the bill but the other parent still needs access to other information in the app.

Perhaps having an "owner" of the account with access to change permissions to "users" of the app. Then allowing others to be set up as "users" of the app.