I like the idea of sending the E mail with the choices and agree that the better you communicate the better things will go. Some international customers have little fabric choices and/or very expensive choices so the additional shipping may be acceptable.
Although we would like to send the entire order to keep the shipping costs down, sometimes that is not possible. Your order of 3 yards of xxx is not in stock, please let us know how you would like us to handle this order.
1: send what we have now and backorder the rest, however, please understand there will be additional shipping charges
2: cut what we have, hold for 10 days and if the rest is not here, we will send what we have and set up a backorder, there will be additional shipping charges for the second shipment
3. cut what we have, hold for 10 days if the rest is not here we will send what we have and there will be no backorder
4. cancel the entire order
If we don't hear from you we will assume you choose method three, please contact us if this is not to your wishes.
If the item(s) is(are) not received by us within the next 30 days the back order will be cancelled and you will be contacted by E Mail.
I would also include in the order that is sent, how the rest of the shipment was handled and refer to the E mail you sent earlier.