I am an international customer so I do have some ideas about this. If it were me, I would contact the customer and ask about the shipping. Personally, I want to get what you have in stock right away! Similarly, I do not want to have to reorder a month down the road. However, since it is not the customer's fault (nor yours) that the items ordered were not in stock, how about splitting the cost of the second shipping with the customer. That way, each party gives a little but neither bear the entire cost themselves. Seems fair to me! Also, if the major part of the order was delayed perhaps the customer would be willing to wait for one shipment and thus both would save money. In that case, I think the customer would have to understand that,as a business, you would either need to charge for the whole order before it is shipped or charge a holding fee. A final idea is to note on your ordering page which fabrics are not presently in stock so that customers can make the decision about ordering up front. If they know a particular fabric is not in stock they can either substitute themselves or make their order knowing they have to wait!