Basic least I think it is.

I shared a Photostream with my wife
Later, I wanted to share that same Photostream with my mother

I assumed that in Photostream on my MBP I could add my mother as a recipient but I could not see that that was possible. So, I ended up creating a new Photostream with the same pictures.

Question is: Can I add recipients to a Photostream after I have created it?

I can imagine that I create a Photostream and share it. Later, someone else wants that same stream, so I have to create a new stream, and so on, and so on. In the end I will have countless streams with the same pictures.

So, are people creating streams based on "albums" and sharing them with people. Or, are they creating streams based on "recipients" and then dumping all the pictures they want to send to that person?