Relationship on field that has aggregation value

victor_erathos,

This solution uses a calculated column in the Target table which summarizes the appropriate amounts in the Sales table. I attempted to solve this via data modeling with a Channel mapping table and an intermediary DistinctChannel table for relationships, but the result wasn't correct for product_id 4 (ON TRADE and OFF TRADE from Sales weren't grouped into the ANY row).

Calculated column in Target table:

actual_sales = 
VAR vYear = YEAR ( Target[month] )
VAR vMonth = MONTH ( Target[month] )
VAR vProduct = Target[product_id]
VAR vChannel = Target[channel]
VAR vTable =
    FILTER (
        Sales,
        YEAR ( Sales[date] ) = vYear
            && MONTH ( Sales[date] ) = vMonth
            && Sales[product_id] = vProduct
            && Sales[channel] = vChannel
    )
VAR vTableAny =
    FILTER (
        Sales,
        YEAR ( Sales[date] ) = vYear
            && MONTH ( Sales[date] ) = vMonth
            && Sales[product_id] = vProduct
    )
VAR vResult =
    SWITCH (
        vChannel,
        "ANY", SUMX ( vTableAny, Sales[value] ),
        SUMX ( vTable, Sales[value] )
    )
RETURN
    vResult

Measures:

Target Sales = SUM ( Target[target_sales] )

Actual Sales = SUM ( Target[actual_sales] )

Achieved = DIVIDE ( [Actual Sales], [Target Sales] )

In the visual, use Product[product_id] and Target[channel], along with the measures above: