@Mmsfoxxie - Everyone has already given you great advice. Early in the morning I flew north to Detroit and had a one-hour layover before flying down to Louisiana. I remember the airport was nice and I didn't have to go far to my connecting flight.
I called the airline and asked what time they recommended between flights. They recommended an hour.
I think you might have a chance if your flight originates at Midway. If it's coming from somewhere else you might have problems. And Chicago to Detroit is probably a shorter flight.
Just this past week we took DS to the airport for a 12:20 American flight. He got a notice it was delayed until 3. We were on the way to get him there when he got another notice it was delayed until 5. We dropped him off before 2, and he finally took off at 5:30. BUT the plane was delayed coming from another city.
I believe the best thing you could do is try to schedule an earlier flight out of Chicago so you don't miss the connecting flight in Detroit. I just don't think 31 minutes is enough time.
Otherwise call the airline and tell them you will need extra help getting to your flight to Atlanta.
However you get there have a wonderful visit with your family!