Q. My husband’s ex-wife and I get along well, and as a result, she thinks she can just walk into our home any time she feels like it. My husband does not want to confront her. He’s happy they are no longer arguing. And since I have a good relationship with her and I’m regarded as the peacemaker in this family, he wants me to be the one to talk to her. He says she won’t get mad at me. I don’t think it’s my place. What’s good ex-etiquette?

A. First, for clarification, I imagine your husband and his co-parent share custody of their kids, they go back and forth between your homes, and you have forged a friendship with his ex. Kudos, based on this difficult dynamic. But with it comes the problem you are experiencing — the other home might become too familiar.

When you run into a situation where boundaries must be reinforced, a good rule of thumb is that the person who is related to the “perpetrator” is the one to address the issue.

I understand why your husband wants you to do it, but if you do, the confrontation may be taken personally and that might upset the balance they have all worked so hard to achieve. Your bonus family is now thriving and your husband is thinking, “You’re friends with her. You tell her not to come over without a warning. If I tell her, she’ll be offended, and we will be back to square one.”

Understandable, but not good ex-etiquette.

It’s time for you and your husband to agree on what boundaries should be in place in your home now that all get along, and then dad takes the lead. When he does, his explanation will carry more weight if he honestly presents his discontent and doesn’t blame it you. A simple, “Please don’t drop by without calling first…” is perfect. Not, “It doesn’t really bother me, but Terri feels uncomfortable when you just walk in.” That’s throwing your partner under the bus.

He must own his feelings, speak succinctly, and be respectful to both you and his co-parent. That’s good ex-etiquette.

Dr. Jann Blackstone is the author of “Ex-etiquette for Parents: Good Behavior After Divorce or Separation,” and the founder of Bonus Families, bonusfamilies.com.