ISEMPTY to evaluate only for connected values

I can resolve this with the following measures

keySiteInSiteTbl = 
IF (
    NOT ISEMPTY (
        CALCULATETABLE ( keyTbl, TREATAS ( VALUES ( keyTbl[site] ), site[site] ) )
    ),
    1,
    -1
)

XYinConditionTbl = 
IF (
    NOT ISEMPTY (
        CALCULATETABLE (
            'condition',
            'condition'[condition] IN { "X", "Y" },
            ALLEXCEPT ( keyTbl, keyTbl[site] )
        )
    ),
    1,
    -1
)
Measure4 = 
VAR _0 =
    IF ( [keySiteInSiteTbl] = 1, [XYinConditionTbl] )
VAR _1 =
    IF (
        _0 = 1,
        "for this site there exists a single row with X or Y in condition tbl",
        IF (
            _0 = -1,
            "for this site there does not exist a single row with X or Y in condition tbl"
        )
    )
RETURN
    _1

But is there an elegant way to solve this by passing a filter in Measure 3?