How do operators allocate materials to products in Katana?

Hello, I have a question about inventory movement within Katana. It was our impression that operators would be able to pull materials from inventory to construct products and allocate them in the app, but that's proving to be difficult. We had planned for there to be a tablet (signed in as an operator) in each inventory room. The Tasks would be a list of products. When operators go into the inventory room they could click on the product (task) they were constructing, and then add the materials/ingredients they were pulling. I realize that the ideal method would be for we (the office folk) to make this material list before hand, except we don't always know what the operators use because each product is customized. And there are so many materials used in each product that it would be impossible for us to get it right. So our thinking that there must be a way for operators to specify what they use. This is the problem. Once operators add a material to the products (tasks) ingredient list, they can't edit the quantity that they're pulling, or delete it to try again. Is there a way within Katana that operators (people on the floor actually building our products) to be able to specify what they're using, how much, and for which product, in the app? How do other businesses that create custom products allocate which materials go into which product without needing someone trained with Katana to walk around to each products and count what was used? And if Katana can't do something like this at the moment, are there any integrations we can use with Katana? We still like all of the other features. Sorry for the long question. I hope it makes sense and if not I can answer any questions. Thank you! -Ryan