J.M.
normally you cant bring extra kids but this is mcdonalds and there will be other kids there anyway. J. call and mention that you will have her cousin in town and ask if you can bring her and cover the extra cost if there is one. Also I'd take them early and let them eat there since they'll want it and the toys if they come later anyway. If it was at any other place I'd J. say that you cant make it, but mcdonalds isnt charging by person that I know of to play in their playland