Reply, then Reply All:

When responding to an email, you have the choice to click Reply or Reply to All.



If you choose Reply, but then decide you want to include "all", you don't have to copy the reply you've created to the clipboard, close the email, and start over again this time pressing "Reply to All".
Instead, even if you first choose just "Reply" you can then click "Reply to All", and Notes will fill in the additional names for you.