Number one don't pack unnecessary items like Teddy Bears or make up.
You will be happy if you take a chair for everyone. Those coleman fold up canvas jobbies are great. and they hold your cup too. What will you be doing there? Fishing? Horseback riding, hiking? Remember you always need to stay as dry as possible. Nothing is worse than wet feet. So extra shoes and plenty of socks. Extra t-shirts and sweats and shorts. Dont forget jackets. Bug protection such as Off or Deep woods . Sun screen, what is your water source? Plan to drink plenty of water. food sources? will there be bears around then you have to keep all food safe from them. Raccoons are attracted to food left out.
Try to stick to basic needs and don't get too fussy. A first aid kit is great. Anyone with allergies should pack their epipens or Claraten as there might be bees, yellow jackets, wasps. Plenty of charged batteries for your cell phones as well as extra batteries (kept dry) for flashlights. Make sure the kids all have their own flashlights because if they use yours of course they will lose them.
A camera. Take plenty of pictures. You are expending a time, money and energy on this trip so document it well it will give you hours of pleasure reviewing it for years to come. Take paper and pen so you can journal. Reading material as there is the potential for down time when you might get bored. Remember you won't have tv and computers for entertainment.
Research some good scarry camp fire stories to tell. Don't get stuck trying to make up some lame campfire story off the cuff. Camp fire stories really stick in kids memories and adds to the excitement of the trip.
Are you taking the dog? if there are porcupines in the area a dog can get into a lot of danger chasing them down. Nothing in Hell is worse than being stuck out in the middle of nowhere with your dog frosted with quills and going into cardiac arrest as you helplessly watch him suffer even die. This is no exageration as this actually happened to me.