I'm sure she will be fine Leasha, but if you are really worried why not make a contingency plan to pick her up after dinner if she is still awake. If she is asleep go catch a movie after dinner and ENJOY yourself! (Hard I know if you are worried). If it makes you feel better, call your SIL every hour to check in. Hey if it all works out you could make this a regular thing to look after each others kids once a month or so, so you can have couple time. Good luck and I don't want to see you on chat tonight!