Q: I'm pretty good friends with my ex. We've been apart for five years, share three kids, and have worked through a lot. Over the last four years we've exchanged presents. Nothing big — just little trinkets, but the kids like it and it's been fun. This year I have a new boyfriend. We are pretty serious, and he doesn't think I should give my ex a present. It's just a silly Christmas sweater I got at a discount store. I know the kids will laugh when their dad opens it and they will be disappointed if we stop. What's good ex-etiquette?

A: When there was a breakup years ago everyone went their separate ways. But now, joint custody and the need to co-parent have changed the breakup family dynamic. It's not that uncommon for divorced parents to work through their issues and for the sake of their children keep former family traditions intact, alter them a bit to coincide with the new lifestyle, or in your case, start a completely new tradition that everyone, particularly the kids, enjoys. The fact that your children are happy and look forward to this tradition is wonderful — as long as you and Dad keep it in perspective and they don't see all the togetherness as a false sign of reconciliation.

New partners come late to the party, and, if your new partner is giving you a hard time, that's a huge red flag. When you come late it's best to blend in, not try to change the rules. That will alienate everyone — you, Dad, but most of all the kids. (Ex-etiquette for parents rule No. 4, "Parents make the rules; bonusparents uphold them.) Not sure if he would be considered a bonusparent at this point, but if the kids figure out that something they like has changed because he's in the picture, he's sabotaged his relationship with them.

Often, new partners act as you have described when they aren't sure where they stand. You said you're "pretty serious," but the implication is there's no commitment for the future, you're just together right now. If he's only insecure in this aspect of the relationship, but no other, it means you haven't been clear about how you feel about him and what you see for your future together.

He may also be intimidated by your close relationship with your ex. Make sure your actions aren't giving him a reason to feel insecure or jealous. Ex-etiquette for Parents rule No. 8 is, "Be honest and straightforward in all your endeavors." Now is the time you talk about your boundaries, how you feel and what you expect — and listen to his thoughts for what he envisions, as well. If it appears that he's a good match, not just for you, but for the lifestyle you lead as you co-parent, then let him know you want him to join the club. If it's too much for him, let him go. That's good ex-etiquette.

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