Case. Grandparents cancel the parents’ rules: “at our place everything is allowed”.
Model. An external node overrides the system’s configuration without coordination — the rules become unstable.
Protocol. Parents set the base invariants and calmly but firmly ask the elders to respect them; the grandparents’ freedom is within those limits.
Lesson. Grandparents’ love is a resource; but parents set the parenting policy.
See Perimeter defense.