I am using a joomla component called fabrik which connects to your database/ and/or database tables and displays the data in the front end of your site in different ways.

You also create forms with fabrik which collects your data and sends it to a table that you specify. However Fabrik doesnt have a standard option to let you send data to multiple tables. BUT It does have a plugin field for the form that allows you to run php when the form is submitted, which would then allow you to send the form data to multiple tables. Problem is i don't know php very well!

In the fabrik documentation they show some php that you can run to insert data into database: here is the link fabrikar.com/wiki/index.php/3.x_Common_PHP_tasks. Useing these methods what php code would i need to run to save my form data to multiple tables in my database?