Conditional auto add product to cart

Hi,

I have a requirement to automatically add a product to the cart if any product from a specific category is added to the cart. The product should be added for free and there can be no more than one free per order but extras can be purchased at full price.

I have tried everything I can think of to find a plugin that will do this but I have always come up short with one of the requirements. To simplify the problem I can create the same product twice, one that is free and one that is paid and hide the free one from view but I’d prefer if there’s a way to do it without making that concession.

Any help is much appreciated.

https://wordpress.org/plugins/woocommerce/