Run DataAssist for the kids names database table. Specify the user_Profile.php page as the results page and don't create a search page.
Then after the wizard runs go to the profile page and add code so that the kids names table is filtered by the same session variable you are using at login to filter the parents recordset on that page.
You will have to update the insert page to store the session variable for the associated parent when inserting child records as well.