If you know when order if processed that fabric is on back order or as soon as you are aware that fabric is not available, send email with the following options: 1- send what is available now, we will notify you when back order is available so you can reorder. 2-Hold entire order for up to 2 weeks, if back order does not come in, send what is available and the back order would have to be reordered.
Would also add to the email that if there was no response within 5 days, you would decide whichever option you decide is best for the company but I would make it consistent for all customers