Welcome to the new development area. You will be glad when your trades are allowed to expand a bit. That is completely normal. As soon as something is in the way, it usually gets cleared. Since you are currently not the owner, no one has to ask you. Small children have no place on construction sites, get used to it. If you have to bring the little one, leave them in the car or keep an eye on them every second. No playground! As soon as it is yours, you can reprimand people and refer to safety on the construction site. Boards with nails are negligent; a firm tone is quite appropriate there. You protect yourself from the point of danger transfer with liability insurance.