Carlos Furtado

I would like to offer my new customers the management of their DNS, in my solution I have created a package in plesk only with the option of DNS management, and I would like that when a customer starts the registration of a new domain, in his shopping cart automatically add this package also for free, and when the customer finishes the process, automatically plesk runs the creation module on my server, but at the moment I can not find the option to add another product automatically when adding the domain, I started looking for a hook or something, does anyone know how I can do this? and is it possible? I welcome any suggestions for my problem