Is it ok to tell a parent what I think about them not inviting my kid to their kid's birthday

So we have a back alley we share with a bunch of kids. They're all friends, and most go to the same school although mine isn't in the same class as the others. One of the kids, let's call her Flow, never invites my child to her birthday, despite inviting all the other kids from our little alley. I don't know the actual reason, but as my child is really good friends with Flow's friends, it appears that Flow's motivation is jealousy.As parents, we were always a little offended by this because we always treat Flow very respectfully, but we let it go. This is the 3rd year this has happened, and my daughter deals with it well and it only seemed to bother her a little. She quickly forgets.Today it's Flow's sister's birthday, and she told my daughter that her sister, Flow, didn't want my daughter to come. So while all the kids play in the alley right in front of my daughter (who's playing by herself in the yard,) she's stuck feeling like she can't go out and play with them. Even when they're in the alley and not in Flow's yard.It seems so selfish of Flow to exclude my daughter. They play together all the time. They share the same friends. In the summer Flow and her sister come over every second day and end up eating dinner here every couple of weeks. My daughter end's up at her place all the time. They all go to the same school together!!!Anyway, my question to all of you is, would it be wrong to tell Flow's father (whom I talk to by text message sometimes) that we're deeply offended by this, or something like that. I just find it so hard to keep these feelings to myself. Their kids are clearly hurting mine and there's no good reason for it.I want to tell him that between him and me ( in other words, I don't want to drag other's into it, certainly not our kids,) but I want to let him know that excluding my daughter like this again and again hurts her, and pisses me off.Part of me knows that a. this will get me no where and b. they have a right to not invite her and don't need to justify their decision.Still, I'm angry and want to express my feelings.Should I tell him politely how I feel? Knowing that it might make things worse for my daughter? Or should I (again) just let it go.Sigh. Any pearls of wisdom would be much appreciated here. via /r/Parenting http://ift.tt/2pQFO5W