How to summarize values with a Matrix when data is in three different tables?

Hi Anonymous 

Please try this measure:

MEASURE =
VAR _PK =
    SELECTEDVALUE ( 'Sub-Tasks'[Parent Key] )
VAR _K =
    SELECTEDVALUE ( 'Sub-Tasks'[Key] )
VAR _vtable =
    SELECTCOLUMNS (
        FILTER (
            CROSSJOIN ( ALLSELECTED ( 'Sub-Tasks' ), ALLSELECTED ( 'Time Spent' ) ),
            'Sub-Tasks'[Key] = 'Time Spent'[Key]
        ),
        "__Key", 'Sub-Tasks'[Parent Key],
        "__Hours", 'Time Spent'[Hours]
    )
RETURN
    IF (
        ISINSCOPE ( 'Sub-Tasks'[Key] ),
        CALCULATE (
            SUM ( 'Time Spent'[Hours] ),
            FILTER ( ALLSELECTED ( 'Time Spent' ), 'Time Spent'[Key] = _K )
        ),
        CALCULATE (
            SUM ( 'Time Spent'[Hours] ),
            FILTER ( ALLSELECTED ( 'Time Spent' ), 'Time Spent'[Key] = _PK )
        )
            + SUMX ( FILTER ( _vtable, [__Key] = _PK ), [__Hours] )
    )

Then create a matrix with the field [Parent Key]and [Key] from 'Sub-Tasks', the result is as follow:

Best Regards

Zhengdong Xu
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