It appears retailers often don't stock sails for a specific brand and size one is seeking. Let's face it windsurfing is not as popular as the good old days. While retailers may not have the selected item in stock, is it possible to place a future order, which they could then bundle with other orders from a brand supplier, e.g. Severne, NP?

From my experience, most windsurfing retailers can handle special orders if the item isn't in stock. You'd contact them with the specific brand and size, and they'll coordinate with the supplier like Severne or NP to include it in a future shipment. It might take a few weeks depending on shipping schedules, but it's a common way to get gear that isn't on the shelf without relying on multiple backorders.