Worth knowing. A group DM with two clients’ people in it is the one place a worker refuses outright rather than picking. Start two group DMs instead.
Slack
Group DMs
A message to the worker and a few people at once. The people in it decide which client it is about.
A group DM is a direct message with the worker and two or more people. The worker answers in it, flat rather than in threads, and decides whose copy answers from who is present.

