Add hidden fixed value to a filter

Hi Giadev ,

Is this what you want to get, when you select A at the slicer, you get the data of A plus the data sum of Z. If you select B at the slicer, you get the data of B plus the data sum of Z.If so，You could try the following dax to create a measure:

measure =
VAR sumz =
    CALCULATE (
        SUM ( 'Table'[Value] ),
        FILTER ( ALL ( 'Table' ), 'Table'[Account] = "Z" )
    )
VAR TABLE2 =
    CALCULATETABLE (
        VALUES ( 'Table'[Account] ),
        FILTER (
            ALL ( 'Table' ),
            'Table'[Account] = SELECTEDVALUE ( 'Table'[Account] )
        )
    )
VAR last =
    IF ( MAX ( 'Table'[Account] ) IN TABLE2, SUM ( 'Table'[Value] ) + sumz, "" )
RETURN
    last

final you will get the below:

Wish  it is helpful for you!

Best Regard

Lucien Wang