Thanks everyone for helping out with all the information and suggestions.

I tried to look for an earlier train from DC to NYC. The ones that would leave us with 2 hours in NYC are selling for over $300 for two tickets. I would consider if they let me switch names. I can take my older son and do the switch. I called Amtrak and was told that I can only cancel my reservation and then change. With the train being sold out, I do not want to risk that. I will keep trying throughout the day. But I won't hold my breath for the two seats to open up. It looks like many people will take the train from DC to NYC. I am a little surprised since there are many bus companies offer $20 one way ride to midtown NY from DC.