Hi @kalista,
I think this is something we would like to do at some point - there's a feature idea about moving messages between channels which I think would cover your use case - can you add your feedback there so we can keep things in one place?
If you have any ideas on how you would like to see this implemented, we would love to hear that as well. For example, I'm imagining the option to "Move" the message, and when selected it opens a dialog where you can choose what channel to move it to. The question then is where does it show up in the channel - I'd guess at the bottom of the channel as a new message, but we might have to change the timestamp to say "Moved from old_channel 1 minute ago" instead of just saying "1 minute ago" like the timestamp does now.
If you have any thoughts on how the design should work, please also add your ideas in the feature idea thread 