Rule of Three when child has limited executive functioning

I have a 13-year-old who has the emotional and executive functioning of a 6-year-old, and has an extremely limited ability to understand cause-and-effect. My 9-year-old has ADHD, so she also functions at about a 7-year-old level. They are both out of control. Any little irritation (sister is too loud, someone's "hurting" the dog, have to pick up a mess, etc.) and they explode into yelling, screaming, slamming around the house, swearing. I feel like the Rule of Three would be appropriate for the situation, but are they developmentally old enough for it to actually work? Or are they just going to be stuck in their bedrooms for days stewing over how much they hate me?