Hi, 
We are a wholesale company, We sell goods in Carton most of the time but a few products we sell in pieces.

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I created a new Unit Category PCS (UNITS), 

PCS (Reference Unit of Measure Category)
1 CTN X 12PC (Bigger than reference UOM) 
CTN X 24PC ("")
CTN X 72PC ("")

I assigned UOM Sales & Purchase to CTN X 72PC for a particular product. 
Lets assume I want to sell only 12PCS of that product, I enter qty as 12 on sales order and I change the default Sales UOM(which is ctn x 72pc) to PCS. Everything is OK so far. 

ISSUE 1 - DELIVERY 
When I do delivery it shows the default product UOM instead of PCS (Sales UOM) - and quantity as 0.17 (ctn x 72pc / 12pc) - difficult in checking while delivery. I managed to add additional columns using ODOO Studio ( Sales Qty and Sales UOM) - 

SOLUTION NEEDED: Is there a way to by which is show Sales qty & UOM in Demand, Quantity and Unit Columns

ISSUE 2 - RETURNS
When I have to do a Sales Return. Odoo doesn't allow Quantity with Decimal Points or considers it as Zero Quantity ( 0.17 (ctn x 72pc / 12pc) )

SOLUTION NEEDED: To show Sales Qty & UOM instead of Product qty & UOM

ISSUE 3 - Rounding OFF
  0.17  -----> ctn x 72pc / 12pc = 0.1666667 - Odoo rounds it off to 2 decimal points. would it give me accurate Quantity on Hand?

Thanks
Fahim