Easy way for who? The question you have to ask is why do they need to be separated. If the ID is made or not made, then the person who asked for the ID will know there is an answer because he is subscribed to the thread and is obviously looking for the answer. That person is really the only one that counts. But, If you are like many of us who enjoy helping others out, then looking in a thread that may or may not have an answer is no big deal, especially compared to the effort it would take to do what you have suggested, sending messages, waiting for answers, and then moving threads. There are hundreds of ID requests made on a daily basis. That's too many hoops to jump through. No Mod has the time for that.
If you want to avoid those threads where you are unsure of whether the ID has been made or not, just look in the threads with no replies.