I agree with the PP, if you are ready to have a career in this business then it's time to get things on YOUR terms. I would never watch kids in the environment you described, way too many safety hazards-if ANYTHING happens regardless of who's house it is, you will be the one responsible.
Your house, your rules-this will probably help in so many aspects, behavior, naps, food etc...
Time to make a change and honestly I don't think caring for family is ideal-too many issues can come up-you are already seeing them. If they are not willing to come to you consider advertising for new kids and start over doing things your way
My guess is you will make more money too!