Convert Rows to column and group in new column

SteveDesmedt  A  dax solution

Measure3 = 
VAR one =
    ADDCOLUMNS (
        src,
        "test",
            VAR exp1 =
                CALCULATE ( MAX ( src[Document Code] ) ) & ":"
                    & CALCULATE (
                        CONCATENATEX (
                            FILTER (
                                ALL ( src ),
                                src[Entry No.] = MAX ( src[Entry No.] )
                                    && src[Document Code] = MAX ( src[Document Code] )
                            ),
                            src[Document Reference],
                            " & ",
                            src[Document Reference]
                        )
                    )
            RETURN
                exp1
    )
VAR two =
    ADDCOLUMNS (
        one,
        "test2",
            CONCATENATEX (
                SUMMARIZE ( FILTER ( one, [Entry No.] = EARLIER ( [Entry No.] ) ), [test] ),
                [test],
                "||",
                [test], ASC
            )
    )
RETURN
    MAXX ( two, [test2] )