Delivery usually means to send to a customer ordered or sold items. When you give out the inventory, you have arrangement to collect them back in a processed form. So it is either you sell raw materials to them and buy another type of product from them for which bills and delivery not must be used to transfer the goods, or, you send them there just to pick them later when they have added their bit of production to it, which isn't a sale and therefore doesn't need delivery note. It a form of delivery but the delivery and goods receipt note in Manager is meant to be issued to customers and suppliers and not manufacturing partners.
You can design a different form that can be used between you and your business partners for the movement of inventory.
Do the business partner return the inventory after they have converted them? if no then it a sale, if yes then you haven't legally transferred the materials to them so why a delivery note?
If they insist on a delivery note create a different company and issue it from there as suggested above and reserve the delivery and receipt note in the main company for your customers and suppliers.
So when you send the inventory to them, you are just changing the location of the inventory because they will be returned, everyone of them and they will pay for damages if they damage any this doesn't constitute a sale and therefore Manager.io Delivery Note tool as it is now is not appropriate.
Design a new form call it maybe "Transfer for further manufacturing form" or something detailing the qty, type etc of inventory transferred there which will be counter signed by your business partners when they arrive there.
Please do you understand?