bill of materials

hi,
if i get an order for i item which contains 5 parts
i have a requirement to make 5 parts
if i book that item into stock the 5 parts are removed from stock
the 5 parts nor the i item are not removed from the requiements until the 1 item has been invoiced
therfore my pivot table always shows thwe requirements for the 5 items
is it possible to look at the 1 item see that it is in stock and remove the 5 items from the requirements

i have attached a file hopefully to explain what i am trying to do
example

very difficuilt to explian but hope this helps

steve