Groceries inventory : how to use UNIT of Measurement of Quantity( Pcs,Box) in spreadsheet

[Bangash]

Dear Expert,
Your help will be appreciated in advance, Mr sintek helped me before. I thanked him again. Now I struck in this stage.

1 st option
I am trying to make groceries store pos. the purchase unit of measurement of quantity is different for all the items. Some are in box which contain 24 pcs, 36 pcs and 12 pcs and some items are in each i.e. only one item. The box bar-code is different than the items it consists.Sale is working for 1001 and 1002 but not for all because I manually putted all the references. for pepsi , in inventory there is 5 box (containing 36 unit) and 24 pcs and if you deduct 30 pcs, in inventory you will find 4 box and 30 pcs which is right but i don't know how to loop to do for the other items

2nd option
with the receipt button I can add all the items to receipt which is fine ,I need help to deduct all the receipt items at onece from inventory list by clicking button 4

for reference the file is attached.