Six clauses, one page, signed by everyone. A template for household technology expectations that survives past the first weekend.
Keep it to one page
Long agreements are never read twice. Six clear clauses covering where devices live overnight, what happens at meals, which apps need approval, how supervision works, what is private, and how the agreement gets revised.
Include the parents
Rules that apply only to children read as control. Rules that apply to the whole household read as values.