Nice one. This makes me wonder if your customer does not weigh the cheeses when they arrive. For the sale order, 0.1 kg could be scrapped (or evaporated). Converting UoMs is also possible from piece to kg, but does his customer ask kilos or pieces or both? (Has each cheese a bar code as serial number e.g.?)

all cheeses are one batch. weight is taken from invoice supplier. they do not register every cheese or its weight. They are as 10pcs in stock. if sold they put 5x cheese on invoice and sum there weight * price per kilo being the lines total price.