While not UM - my daughter was 16 when she headed home from the rest of us a few years ago. It was her first time traveling along.

Simple hops: MCO-ATL-CHA, but weather intervened. She ended up getting stranded in ATL - not old enough for car or even to check into hotel.

Of course the airport was like black Friday - but everybody trying to leave, not get in. I tried feverishly over the phone to get somebody to pay attention to her in all the chaos. It wasn't long before a red coat noticed her and took care of her - to a special room that Delta has for UMs if they get stranded/overnight or even just long layover. It had food, snacks, blankets, playstations, etc... A kids paradise. Supervised by several all night long.

She came out of the experience (got a flight the next morning) loving the whole experience.

All this to say, if things go south on connections, Delta takes care of them.