Method to Define Expenses when Sharing Costs

[KJ65]

My question involves child support in the State of: VA

My ex-wife and I split custody of my daughter. My daughter is heavily involved in dance and travels nationally to compete. When we went to court to redo child suppport in April 08, the judge stated that we should split these dance costs 50/50.
I just took my daughter to a dance competition for a week in Myrtle Beach.
We shared a hotel with another family and paid approx $800 for the week (half of the cost). I also paid several hundred in gas and food costs.

My ex and I talked about this and she agreed to give my daughter "spending money" so she would have some funds of her own. My ex gave my daughter $100. When I told her that she would need to help me with the expenses, and hoped to get some help before hand, my ex said that she had given the $100 and I could use that as her half of the food money.! That would make me the bad guy to tell my daughter that she had to use her spending money on food.

Do I have to subtract that $100 from her portion, since she refused to tell her daughter that it was for food, said if I wanted help with food, I would need to get it from my daughter????

More importantly, how do I determine what portion of my expenses should be charged to my ex. My ex has refused to take our daughter to any out of town competitions since we separated in 04. So, every year I am forced to take my vacation and spend a week in the summer at a dance competition. I could refuse to go also but then my daughter would suffer, not my ex. I want to go and be with my daughter.

My new wife and our two kids stayed in the hotel with my daughter and I. Does this change the issue at all? Can I charge my ex for half of the $800 lodging costs?

Can I charge her for half of gas costs?

Can I divide the food bill totals by the # of people eating and charge her for that part? Or, will I need to itemize, to prove exactly what my daughter ate and charge her for half of that?

My lawyer says that I should think of this like neither of us went and what would I pay some other family to take my daughter with them. That doesn't seem fair to me. If someone else was already going and agreed to take my daughter also, I have no idea what they would charge me for lodging. How would I know that?