@FirstKid2College - They hand out lanyards with names and some other info for students, and stickers for parents. That is what is supposed to help them identify who is with the group for transportation, food, etc. I think you should probably just admit what happened. They may not have food for you, but I would think they would still let you in the initial meetings, which were helpful, and they should still let you take the shuttle up to the Mount Vernon campus.
We live in DC, so we took the Metro to the event… I doubt they provide discounted parking, because there just isn’t much to be had. There are a number of city lots around, you just have to look for them. They shouldn’t be full before 8am. You’ll pay somewhere around $20-40 for the day. I don’t park downtown much.