Shared Photo Stream Clarification

So pre-iOS 6, my wife and I shared a single photo stream on my iCloud account. I took a picture, it showed up on her phone, she took a picture, it showed up on my phone. It was awesome having everything we took in one place.

I had to change my wifes default iCloud account to hers, however, so that she can back up her data to her own iCloud (I was running out of space) so we can't share that single photostream now.

But now with iOS 6, share photo streams have come about. This is an okay workaround, but I have a question.

Can you not share automatically the pictures you take with a shared photo stream, or you do you always have to click "add" and then select the photos you want to appear in that stream?

It worked great when it just did it automatically..