In SOP you can now create a Return from a Sales Order.  In these days of prices fluctuating a lot due to inflation, its important to get the item cost correct on Sage.  If stock is added at a value into Sage, when you are using FIFO and adding it to an Order, it will use the average cost - as per : http://desktophelp.sage.co.uk/sage200/professional/Content/SOP/SOPOrderStandardItem.htm

If there is only 1 cost on an item from the location selected, it will use the cost of the stock in the location, which can be different to the cost on the SO.  If you raise a Return from a Sales Order, it copied the cost from the SO, so when you receive it, it uses the cost from the return, which will be incorrect and cause confusion.  I understand its not using Actual costing, though really, picking up the average cost could be very wrong depending on what the average is, and would be good if there was a warning or something prompting the selection of the cost, as I understand it may be ok for some customers, but it can cause headaches for others.