We mainly sell paint in a retail shop. Now we are getting contracting work that supplies paint and labour. When I invoice the client, the invoice will state two lines, product and labour. The invoice is created under the customers code. Now we need to book materials used to the same account to adjust our stockholding on the retail floor. What will be the simplest process to follow to book products from the shop floor to the client code to see what our final cost for the job is without creating additional sales?