Use @everyone tag in Clubs to notify everyone
Also use the @here tag to notify online people playing now.
You should have a corresponding setting as well:
"Who can use the @everyone and @here tag?:" > (Owners/Admins default)
I like the idea of reaching out to the whole group or the group members who are online all at one time.
COG Integrity commented
how is no one begging for this? it seems to low priority.