Thanks for your Reply Tygb !
If I'm the creator of an album and I put photos and videos from my photo stream in the shared album and then I transfer photos and videos to my mac or pc to make free space on my phone. what would happen to those photos and videos?
You agree with me that I can not keep photos and videos for long time on my phone and I have to remove them from the phone? The issue is , I have the back up copy of all my photos and videos but gathering them in an album was the feature I was looking for. So it seams having shared albums is useless since you can not guarantee keeping them for long time.
So the question is how I can have a shared album in Mac which I can back it up as Album including all likes and comments ? my answer is " i can not have it" . Is there any alternate way ?