Working at two schools is not a problem. Everything is web-based, so you can access your lesson plans from anywhere. You can give your principals access to your plans simply by sharing your plans with them. If your school or district has purchased My Lesson Planner for you, your principals already have access to your plans, so you won't even have to give them sharing or viewing privileges.
Sometimes schools have different requirements for lesson planning, so you may need to set up more than one template. You can have as many templates as you need, and if you need help setting them up, all you have to do is ask! We are here to help you.