Enable/Disable Promo Code Function for Pre-Order Manager App

Hi, 

Pre-order items are products that are not in stock yet these pre-order items should not be provided a coupon code. As user we should be able to have a function where we can enable and disable if we want pre-order items to use a coupon code. 

I have a coupon code on my website and when there's a pre-order item my customers can use the coupon code and they get a discount off. This function needs to be added in. As a user I wish this function I can control. I can control whether customer are able to use a coupon code or not a coupon code. 

I hope there are other businesses out there who is having the same difficulty. 

Thanks.