I believe adding custom fields for addons would be a huge feature to add to the WHMCS system.
With our products, almost every order gets an add on with it which needs to be customized to the client's needs. Right now we have to have all of the custom fields for the addons along with our main custom fields for the products. To me this could be done way better.
Please add this WHMCS!
Configurable options and custom fields for Product Addons
Client side product configurations of addon products are not currently shown on the order form.I would like for customers to be able to select configurable options and custom fields for product addons, in the same way that is currently possible for products.