if you have an existing post that you want to show in a different channel, you can edit the message and cross-post. This will add the top-level post to the different channel, but will not include the full set of replies. We will keep this request in mind as we evolve the cross-posting feature in the future and update if the status changes.
Details on cross posting can be found here: https://support.office.com/article/cross-post-a-channel-conversation-in-teams-9c1252a3-67ef-498e-a7c1-dd7147b3d295.
The team continues to make progress on this. We will share more details as we have them.Paul Jefferson commented
If it isn't too late we would be interested in testing the group calendar feature at our school.
Due to a priority shift this request has slipped to the backlog. I hate to bring bad news. I will continue to provide the feature team your feedback and votes.
Hopefully this will move back up in the queue soon.