Add hidden fields in a WooCommerce Form

Project ist based on WooCommerce. Registered users can add products in frontend over WP User Frontend Pro. Process: User adds one product over the fronted. Directly after this he adds 3 other products. The first product should be added in the same category named liked the username, the other 3 products should be added to the child-category "all products" from the first. The products should be also linked/connected over the meta key"_upsell_ids". So I need: Hidden category-field for the first product 1. Exclude all categories except the categorie with the same name as the user (For example: user has the name "John Doe", so all other categories should be excluded, except "John Doe") and added to this. Hidden fields for the 3 other products 2. Add the first product to the meta_key: "_upsell_ids" of every of the 3 article 3. Add the 3 other products to the meta_key: "_upsell_ids" of the first product 4. Add the products to the child-category of the first added product (for example "all-products-john_doe").