I understand, we had similar issues. We sell items either in pieces or Boxes. The box Qty can vary from item to item. So we wanted to know how many boxes of merchandise do we have. Similar to you. Since we only have two UOM per item it was controllable with some mod. If we had many different UOM it would have been messier.
First we needed to get the UOM quanitities from the Item Unit Of Measure Table.
So I create three new fields on the item table. All Flowfields.
1) Base UOM Qty
Calcformula: Lookup("Item Unit of Measure"."Qty. per Unit of Measure" WHERE (Item No.=FIELD(No.),Code=FIELD(Base Unit of Measure)))
2)Sales UOM Qty
CalcFormula:Lookup("Item Unit of Measure"."Qty. per Unit of Measure" WHERE (Item No.=FIELD(No.),Code=FIELD(Sales Unit of Measure)))
3)Purch UOM Qty
Lookup("Item Unit of Measure"."Qty. per Unit of Measure" WHERE (Item No.=FIELD(No.),Code=FIELD(Purch. Unit of Measure)))
Now I have a number on the item table (don't Forget Your CALCFIELDS) that I can use to divide my Qty by to give me my qty by sales uom. Which is the one we use 99.99% of the time. When a picker goes to the shelf he doesn;t need to know we have 144 pieces. He needs to know we have 12 boxes of 12 since we sell them in boxes only. So I created a "Warehouse" form that shows the qty's in the values they need to see. I calc'd the Qty
CALCFIELDS("Sales UOM Qty");
IF "Sales UOM Qty" = 0
THEN MESSAGE('Error On Item %1',"No.")
ELSE VisualQOH := Quantity / "Sales UOM Qty"; with Visual QOH as the SourceExp of my field.
Now if you wanted to make a field on the item card to calc this you will need a developers license. We use these UOM Qty's mostly on reports and it's a bit easier because we don't have to bring that info in from another table.
I don;t know if I really answered your question, but it sounds like you will need a mod. and for that you should contact your NAv partner for a quote. they know your needs better than us. Perhaps an addition to the "item statistics" that can show the breakdown you are looking for.
