Once you start researching, the volume of information grows at a startling rate. Much of it will turn out to be useless, but you cannot immediately tell the wheat from the chaff. You had better form the habit of recording and organizing as you go or there will be total chaos in a very short time. Label the pictures. With complete information.
Every family has a bunch of mystery pictures.
We know they are relatives, but nobody knows their names, or when the photos were taken, or where. Don't let more pictures become mysteries. Since the one relative who still recognizes the oldest people may not be here much longer, this may just be another aspect of interviewing the living.