i have this exact same problem with DF family. Everytime i get DD2 into a good routine, we have a family thing to go to and everyone wants a cuddle and the routine goes out the window because she gets over stimulated.
I now keep her out of sight when it all gets to much for her, like i put the stroller in the corner with me in front of it so that its obvious (to most people) that she is off limits for awhile. I figure if i have to say no then its worth possibly denting someones feelings to save myself from having a horrible unsettled night. And i make it very clear that when she is asleep she isnt to be cuddled or touched because i dont want her expecting to be cuddled to sleep at home.