Link feature requests to a product

WooCommerce and EDD products are normal WP posts, so this could also read "Link a feature request to another post". I have multiple products and want to separate the requests for each product without abusing the Category taxonomy. I think this has the following aspects: 1. In Admin we need to link every request to another post (we might select the available post types in the Settings page) 2. The shortcode gets a new attribute (e.g. `belongs_to="10"`) to filter the displayed requests 3. When creating a new request from the frontend, the new request is automatically linked with the "belongs_to" post when it is saved. Btw: Another option would be to have a second taxonomy like "Board" or "Group" that collects feature requests that belong to the same Product.