Hi @grogne ...
I'm sorry to see that your question has been sitting out here unanswered since late August. I looked at your question and then was going to give you a link to this Commons Guide, How do I update a resource I previously shared to Commons?, but I see that you've already posted a similar question there...which also hasn't been answered yet. I'm going to share your question with someone at Instructure who works with Commons, and hopefully you'll get a response soon.
I'm going to have this same question soon. We just turned on commons last week and the thought from the ID team is that it would be great to use commons as a way to house course masters. A change in commons would be pushed out to live courses. But then what if a professor makes a change to the individual course?
Were you able to find an answer to your question? I am going to go ahead and mark this question as answered because there hasn't been any more activity in a while so I assume that you have the information that you need. If you still have a question about this or if you have information that you would like to share with the community, by all means, please do come back and leave a comment. Also, if this question has been answered by one of the previous replies, please feel free to mark that answer as correct.