You could get around it by creating a 2-D array and adding the names of the tags for a group of sounds to a column/row - this would allow you to place a sound in multiple groups.
When you want to affect all sounds in a group you could then run a loop on that group, pointing the tag field in the relevant audio action.
e.g.
you have sounds tagged "sfx_A", "sfx_B", "sfx_C", "sfx_D"
array_soundGroups has three groups of 3 sounds:
0: ("A", "B", "C"),
1: ("B", "C", "D"),
2: ("D", "B", "A"),
To turn off group 2:
for "i"=0 to array_soundGroups.Height-1)
stop sound tag "sfx_"&array_soundGroups@(2,loopindex("i"))