Stock issue with creating invoices from sales orders / invoice draws more stock than available
Basically, we have a customer that places a large weekly order. In most cases we won't have all items in stock to supply the order in FULL, so some items go into back order. When we receive one of these orders, we always create a sales order, then create one invoice from that sales order and any other previous sales orders that may have other items that have in the meantime become available.
Basically the process is: create invoice > tick "select all sales orders"> "create invoice for selected items".
So the invoice would typically be for recently become available items from 5-6 sales orders.
Now, give example of item "X" of which we currently have 2 units come into stock. However, there are 4 in total on two seperate sales orders (2 on each sales order).
The issue now is that invoice will have listed all 4 items despite only 2 being in stock. Stock goes into -2.
When we create an invoice we send it to the customer to get paid. Once paid we pack the items for dispatch. The above issue then arises when we go to pack and realise that the invoice has drawn 4 items from sales orders where it should have only drawn 2 (starting from the oldest sales order), as only 2 were in stock.
Contacting RECKON, they said we have to manually adjust the invoices, but I simply can't believe this is how other RECKON users deal with this issue. These invoices commonly have up to 30 lines, and it is impossible to manually detect that there is an item on line 4 and again on line 26 (for example) and for us to know that those items aren't actually in stock in full numbers for all sales orders.
Anyone have a solution for this? We can't believe the system can't handle it better as it leaves so much room for system errors that the system should be capable of handling.