add manual temporary product item to order in admin dashboard

I have a rental company where I rent out party items. Sometimes it happens that a customer indicates in the comments of his request that he also needs certain items that I do not have in my assortment and therefore do not have in my webshop. However, I can often achieve this through other partners. What I want to be able to add to the order as an admin is a product, but as a free input field. By default, Woocommerce allows you to choose from the list of products to add multiple products to the order. But since the additional requested items are not in my assortment, I want to be able to add them as a product to only that specific order using a free input field. I currently do this using the ‘costs’ button, but then it does not appear in the product list on the packing slips and invoices, but at the bottom as costs in the price summary. This is currently causing confusion among customers. So what is possible here?