Q: So each year when Halloween rolls around, your column talks about trick-or-treating with your partner's ex and the kids and I always thought, "How stupid. Who would really hang with their partner's ex on a holiday?" Well, this year, I met a man who has an ex and three kids and they wanted me to go trick-or-treating with them this year. It all felt so unnatural to me. What's good ex-etiquette?

A: I have to laugh because I have found that what you most fear often becomes your destiny — and here you are like so many, trying to navigate a new relationship with a partner who has kids and an ex. I don't know how long you have been dating, but if they're asking you to join them trick-or-treating with the kids, they both (your partner and the ex) see you as a permanent fixture, which means there will be many more joint holidays to come — especially this time of year — so if this person is your person — get used to it. Or don't, but understand that if you appear to be all in, then pull back, they might take it personally and that can ultimately affect your relationship. Have your answers ready.

For the record, let's look at what your future might hold.

First, do you like his kids? More important, do you like being around his kids? Because from this point forward, you will have three children in your life. They aren't yours and you will have little say in any decisionmaking, but it sounds like these are hands-on parents who want you to be a member of the club, so there you will be at every milestone their children face. Is that what you want?

Second, how do you feel about the ex? Because she will not be going away soon, and if you choose to continue with this partner, I predict additional ex interaction — not less. Make your boundaries clear, which means everyone — you, your partner and the ex, must have a clear picture of how involved you really want to be, otherwise expectations (on all parts) will not be met and resentment will set in. Once that happens you may find yourself labeled as the outsider, wondering where your partner's allegiance really lies — to the ex, or to you. Those feelings are difficult to overcome and something that new partners don't like to discuss. I have often heard, "I sound so needy. I hate to bring it up." But in the new partner's mind, they wonder about their true importance and that eats at the stability of the relationship.

If all this feels unnatural, take a serious look at it. A ready-made family is not for everyone. I've mapped out the obstacles and confronting them directly is the key. If you think conforming to this new relationship model will be difficult for you, don't attempt it. 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.