Inventory Tracking and Order Fulfillment

Hi AnAnalyst 

Your measure [Sum of Ending Stock] in your model doesn't seem to work.

Would something like this help?

zBalance = 
VAR _CurrentStock =
    CALCULATE(
        SUM( 'Current Stock'[Current Stock] ),
        FILTER(
            ALL( 'Date' ),
            'Date'[Date] <= MAX( 'Date'[Date] )
        )
    )
VAR _CustomerOrders =
    CALCULATE(
        SUM( 'Customer Orders'[Order Quantity] ),
        FILTER(
            ALL( 'Date' ),
            'Date'[Date] <= MAX( 'Date'[Date] )
        )
    ) * -1
VAR _SupplierOrders =
    CALCULATE(
        SUM( 'Supplier Orders'[Quantity] ),
        FILTER(
            ALL( 'Date' ),
            'Date'[Date] <= MAX( 'Date'[Date] )
        )
    )
VAR _Total = _CurrentStock + _CustomerOrders + _SupplierOrders
RETURN
    _Total

Let me know if this helps or if you have any questions.

Added:

Regarding you questons...

1.  Any time [zBalance] is less than 0 would indicate a lack of stock.

2.  I'm not sure of your company's procedures/rules but I think that might take a little more work.

Sorry I had to add this.  After re-reading I realized that you had other requiements besides the running balance.