Adding a Incus machine with containers to a existing Cluster, and removing working Cluster member from cluster into stand alone

I am always having issues upgrading nodes, and in some mission critical applications I am starting to think that I am better off being standalone.
So the question what happens to running containers if I do a incus cluster remove. Can I do it while the containers are running in node I want to remove? On the converse side can I add a node with running containers using incus cluster add. All this without rebooting and containers running none stop.

I would play with it myself but since this is a production cluster with real working containers I decided not to play with it unless I get ‘official’ approval from the top incus brains…

It will refuse to remove the cluster member so long as it has things on it.
Similarly you can only join an empty server into a cluster.

Thank you for your answer.
SO I guess if I have 4 machines A,B,C,D and I remove A,B,C, from cluster individually since they have nothing then D is left by itself. I can then rejoin A,B,C into a new Cluster and D stays by itself as a cluster of one. And this can be done without a reboot?
Also if I remember a two node cluster is really not a full cluster. Is that correct?

Yeah, a 2 machine cluster isn’t HA, it’s still a cluster but if whatever machine is running the database goes down, the other server will not respond until that machine comes back.