Adding new Prestashop Theme child and adding new functionality to CartController

[Ani]

Hi everybody! I'm new in Prestashop as developer, I made my new theme child (theme1313) to allow multiple selection of sizes and color in same transaction.

I construct my theme child "theme1313_multiple_select" and its father is theme1313. Now I need to update CartController to receive an array of product attributes, quantities to add in Cart.

I dont Know how can I update CartController... which solution do you consider is better?

1) in Prestashop root in path /override/classes/controllers and CartController and make my changes

2) Add this path /override/classes/controllers/CartContrller.php inside my theme1313_multiple_select folder? Is it possible?

3) Another right solution?

Thanks a lot!