Add option page

How can i add a option to the checkout or cart page, Let's say you go to TournamentNewPayment.php

you select add to cart>> this can go to the CART or another page saying would you like to add side-pots "product", the client can say no thanks and proceed to cart or select yes and add to cart and proceed to check out.

Basically this system is for golf tournaments, they choose how many players and add to cart, then an option to join and pay for the side-pots for the tournament.

I hope this info is clear enough.

thanks

create a page for adding the side pots product to the cart, in the add to cart behavior for the tournament product, set the redirect after to point to the side pots product page.