This is one of the more painful positions in co-parenting, because it can feel like there's nothing to do except watch a rule you care about get ignored every other week. There are real limits to what you can control here — but there's more available to you than it might feel like right now.
Start with what's actually not in your control
You can't make another adult enforce a rule they've decided not to enforce, and unless there's a formal parenting plan with specific, enforceable language a court has ordered, there's usually no mechanism to compel it. It's worth being honest with yourself about that early, because a lot of frustration in this situation comes from treating an uncontrollable variable as if it should be controllable with enough of the right argument.
What is in your control
Your own house being completely consistent. This matters more than it might seem in the moment — a kid who knows one house is entirely predictable still benefits from that, even if the other house isn't. Consistency in one place is not nothing.
How you talk to your kid about the gap. Avoid criticizing your co-parent directly to your child, even when it's tempting — it puts the kid in a loyalty bind rather than solving anything. A neutral version like "the rule here is the rule here" holds up better over time than commentary on the other house.
Whether you escalate through the right channel. If this is affecting your child in a documentable way — grades slipping, sleep disruption, behavioral changes — that's different from a values disagreement, and may be worth raising with a family mediator, therapist, or (if you have one) referencing directly against language in an existing parenting plan.
A lower-conflict way to try again
If you haven't already tried a low-pressure written proposal — not a confrontation, just a short, specific document — it's worth one more attempt before assuming the conversation is closed. A one-page starter document is far less likely to trigger defensiveness than a formal, multi-page request. We built exactly that as a free download — see our free starter agreement if you want something short enough to send without it reading as an ultimatum.
When to let the bigger picture matter more
It's worth remembering that a kid having one inconsistent household and one consistent one is a very different situation than two inconsistent households. The house you control still matters, even on the days it doesn't feel like it changes anything.