"I have one problem though, I paid for everything, so how would I split up?"
I'm not sure what you mean by this. Surely you are not holding the incidental spending money for each individual? I don't think that's a great idea when more than one nuclear family is concerned, bound to cause resentment all over the place. If you absolutely had to do that and were staying onsite, you could put pre-set spending limits on the room cards, I suppose. Park passes are best purchased in advance; they are less expensive that way, anyway. If you are buying them, buy them as a gift, photocopy the backs, and just pass them out once, preferably before you get there. If they lose them, you can refer to your receipts for replacements, but I'd read the riot act about losing them.
Normally, in a multiple-family situation, incidentals, including meals, are on a cash basis within each nuclear family, unless one family is hosting a particular meal, in which case it is their treat. One family might make the room reservations and put down the initial deposits, but then collect all of the lodging money for the trip before departing. NEVER let a trip begin on the theory that a travelling companion will pay you back later; that is a recipe for disaster--either it is a gift, or it isn't, but don't be anyone else's creditor. If the purchase you are making is going to be non-refundable, such as air tickets, don't do it unless a paying member of the other family is actually present at the time you make the purchase, cc in hand.