Thanks for your reply. I meant the zipper fabric area which is marked in attached picture. I think it’s not necessary, is it? We’re very glad to make a trial sample for you.Since you don’t want a laminated membrane , we can only make waterproof on fabric. It’s something like water repellent.Now we’re still having an internal discussion for this project as we must select the no harmful & safe waterproofing agent for baby products. As soon as we have any update, will let you know immediately.Thanks for your patience.