You deal with 2 SQL tables, so you need to interface the 2 tables files (php)
For instance :
Main table : Account (generated by Cook)
Linked table : Users (existing table)
TODO : (frame)
1. First of all, in the BUILDER
- Create your two tables (even the users table)
- Fill with all the users fields (cloned, but you can create less fields)
- In the main TABLE, create a FK to the users table (short name: 'user' for instance)
- In the LAYOUTS, instance the 1:1 joined fields (In forms, you cannot for the moment)
2. In LAYOUTS FORMS php files
- Instance your fields manually* (with JDom, it is really easy)
*using the joined name alias (_user_myfield for instance)
3. In the MODEL of the main table (account) :
- receive the POST and separate the VALUES that not concern the main table (starting with '_user_')
- deal with the store() and co. functions, calling the second table class (users : native of joomla in our case)
- manage the idkey in operations (ADD-EDIT-DELETE)
That all I can say for the moment.
I should do a tutorial for that.