It is also possible to join two classes into one alternative form. This option is currently available only for the User and User - Settings system tables.
1. When creating an alternative form for the User system table, you have the option to check the Combine with user settings checkbox.
2. Now if you switch to the Fields tab, you will see that in addition to the original fields contained in the Users table, fields from the User - Settings table are also available in the list, as you can see in the following screenshot: