How to create more than one group that include the same value, using a slicer?

Hi,

Please take following steps:

1)Create a group slicer table as below by Enter Data:

2)Try this measure:

Measure = 
SWITCH (
    SELECTEDVALUE ( 'Table 2'[Groups] ),
    "Group 1", IF ( SELECTEDVALUE ( 'Table'[Clients] ) IN { "Alpha", "Bravo", "Charlie" }, 1 ),
    "Group 2", IF ( SELECTEDVALUE ( 'Table'[Clients] ) IN { "Delta", "Echo" }, 1 ),
    "Group 3", IF ( SELECTEDVALUE ( 'Table'[Clients] ) IN { "Alpha", "Charlie", "Echo" }, 1 )
)

3)Apply this measure to the original table by setting measure=1.

  When selecting one value in group slicer, the result shows:

See my attached pbix file.

Best Regards,

Giotto