Q: How do I deal with being the last to know everything? It's like my fiancé is still in a relationship with his ex and then there's me. For example, the kids had a doctor's appointment. They all ended up at our house afterward. Evidently, there were plans to go for ice cream after the doctor's, but everyone forgot to tell me.

So, my guy, the ex, their kids are all saying, "Let's go!" and I'm wondering, "Where?" I caught on and jumped in the car, but I feel like I'm the odd man out. When does this normalize? When do I get to have a relationship with just my fiancé? Not his ex, not his kids?

A: Never? You're marrying a man with children, and that relationship is forever. They aren't going away. Considering what parenting plan mom and dad follow, your private time will be when the kids are with their mother. If you're looking for something else, this may not be the guy for you.

If it is as you have explained, it does sound like dad is pretty close to his ex — and if he doesn't watch it, those blurry boundaries can get messy. Then you have confused kids and angry fiancés. Dad has to reassess his priorities. In other words, you can easily be successful at co-parenting and not spend the afternoon having ice cream with your ex after a doctor's appointment — even if you invite your kids and your fiancé. Too much togetherness can be confusing for everyone, particularly the kids.

There are certainly times that are appropriate for exes to spend together — their kids' birthday parties, if they get along well enough, possibly watching the kids' extracurricular activities. Just be careful. Most kids of divorce pine for a time when dad and mom will get back together. All this hanging out can look like that might happen. It would be very easy for the kids to see you as the interloper standing in the way of their mom and dad reconciling. If it gets to that point, it will be difficult to go backward.

So, if this is the man you choose, you will not have a conventional relationship in the sense that it's just you and him sailing off into the sunset. The parents have an already established parenting plan that they feel is working. Based on that, this is solid advice: Don't try to develop new policies by yourself. Coordinating efforts with exes, fiancés, and kids is a well-choreographed dance. Dad should take the lead.

Your first step is to talk with your fiancé. It sounds as if no one has truly considered what your role should be in this family. Figure that out. That would be a great place to start the conversation.

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