Co-parenting would be easy if both parents always agreed. In real life, many parents share custody with someone they find hard to talk to: messages that turn into arguments, last-minute changes, old conflicts that creep into every conversation about pick-up times.

You can't control how your ex communicates. You can control how you respond, and that alone can change the temperature of your co-parenting relationship. Here are practical, proven-in-practice strategies for co-parenting with a difficult ex, including the widely used BIFF method.

Start with the goal: communication about the kids

The most helpful shift for many parents is to treat co-parenting like a business relationship whose only business is the children. Your messages don't need to resolve the past, prove a point, or get an apology. They need to get the kids to soccer practice, share the pediatrician's advice, and confirm the holiday plan.

Before sending anything, ask yourself: Does this message help us take care of the kids? If not, it probably doesn't need to be sent.

The BIFF method: Brief, Informative, Friendly, Firm

The BIFF response was developed by Bill Eddy, a lawyer, therapist and mediator who co-founded the High Conflict Institute. He describes it in his book BIFF: Quick Responses to High-Conflict People. It's a simple framework for replying to hostile or emotionally charged messages, and it's popular among co-parents because it's easy to remember.

A BIFF response is:

Brief. A few sentences. Long replies give the other person more to react to.
Informative. Stick to useful, neutral facts. Correct a misstatement only if needed, calmly and without arguing.
Friendly. A courteous tone: "Thanks for letting me know," "Hope the trip went well." Not warm and personal, just civil.
Firm. Close the topic. Give a clear answer or a clear choice, and don't invite further debate.

A BIFF example

Say you receive this message:

"Typical. You ALWAYS change plans at the last minute. The kids can't count on you for anything. I'm not rearranging my weekend again because you can't get your act together."

A reactive reply defends, counterattacks, and keeps the argument going. A BIFF reply might look like this:

"Thanks for your message. My work shift changed this morning. I can pick the kids up at 6 p.m. Friday instead of 5 p.m., or I can keep the original time and have my mom pick them up at 5. Please let me know which works by Thursday noon. Thanks."

It's brief, it shares the relevant facts, it's polite, and it ends with a clear choice and a deadline. It doesn't respond to "typical" or "always." Nothing in it invites a fight.

More strategies that help

Choose the right channel

Phone calls and in-person conversations can escalate quickly. Many parents find written communication (email, text, or a co-parenting app) easier to keep calm, and it creates a record. Some parenting plans specify how parents will communicate; follow what yours says.

Keep messages to one topic

Bundling five issues into one message makes it easy for things to derail. One message, one topic, one clear question.

Set a response window

You don't have to answer instantly. Unless something is urgent, waiting a few hours (or until the next morning) lets you reply with a clear head. Some co-parents agree on a reasonable response time, like 24 hours for non-urgent matters.

Don't use the kids as messengers

Asking children to carry messages, or asking them about the other parent's personal life, puts them in the middle. Communicate directly with your co-parent, even when it's hard.

Be specific about times, dates and places

Many conflicts come from vague plans. "Sometime Saturday" is an invitation to disagree. "Saturday at 10 a.m. at the library parking lot" is not.

Rely on the parenting plan

When there's a dispute about the schedule, point back to what your plan or court order says instead of debating who's being unreasonable. A clear, detailed plan (see our parenting plan checklist) prevents many arguments before they start.

Keep neutral records

Keep a factual record of schedule changes, agreed swaps and expenses. Not to build a case against your ex, but so that "wait, what did we agree on?" has an objective answer. If a dispute ever does reach a mediator or court, organized, factual records are far more useful than angry message threads.

Consider outside help

Parenting coordinators, mediators and co-parenting counselors can help high-conflict families find workable routines. If there are concerns about safety, abuse or threats, contact local law enforcement or a family law attorney. No communication technique replaces protection when someone is at risk.

Take care of yourself, too

Dealing with a high-conflict co-parent is draining. A few things that help many parents:

Have a friend, therapist or support group to vent to, so your messages to your ex don't have to carry your frustration.
Let small things go. Not every mistake needs a response.
Focus on what happens in your home. You can give your kids a calm, consistent home even if you can't change the other one.

Structure reduces friction

Many co-parenting fights aren't really about the big issues. They're about the schedule: whose weekend it is, whether a swap was agreed, who paid for the field trip. The more of that is clear and visible to both parents, the less there is to argue about. Choosing a schedule that fits your family, whether that's 2-2-3 or every other weekend, and a holiday plan that's written down years ahead, removes a lot of opportunities for conflict.

This article is for informational purposes and isn't legal advice. Custody rules vary by state—talk to a family law attorney or mediator.

A calmer, more neutral way to coordinate

Alternly gives both parents the same calendar, so the schedule isn't up for debate. Day swaps are proposed and accepted in the app, with a full history of what was agreed. With premium, a shared message board keeps school paperwork and questions in one neutral thread, and shared expenses show one running balance instead of an argument. Create your free custody calendar and give your co-parenting a little more structure.

Co-Parenting With a Difficult Ex: Communication Strategies