Depending on your state, you might not need to justify it. Check out HSLDA's reference for homeschool laws in your state. If you live in a state that has some regulations, I encourage you to find out how unschoolers make it work where you live. Here in Pennsylvania (a highly regulated state), I recommend Unschool Rules, a fabulous resource for unschoolers in any state. As far as concerned family and friends, how you handle that is up to you. You can find some great tips in How to Conquer Homeschool Joy Suckers.