How to add dope sheet channel to group

Meaning, I made a grouped multiple channels (ctrl+G) in the dope sheet (all of the head bones), but i did not add the neck to that group. Now, looking back, I’m wishing I had added the neck to that group. So the group already exists (like 30ish bones), and I just want to add one more bone to that group.

Also, un-grouping didn’t work as I was expecting. When you ungroup the channel, it doesn’t revert to the groups that previously existed. It just leaves you with everything ungrouped. That’s the case or am I doing it wrong?

Thank you in advance! thank you thank you.

Did you ever figure this out?