Dear concerned stepmom:

I agree with you that dying a 4-year-old's hair does give her the message that she's not OK as she is. She's going to get that message a lot in her lifetime, given how many industries are dependent on girls and women worrying about how they look! But criticizing another parent's decisions after the fact is not a great way to increase your influence with her. Most parents take offense at advice and criticism, and it just backfires--if it goes over wrong, you lose the good will you might have with her, and your thinking is less likely to be considered in the future.

What I would suggest is listening to her. There are a myriad of reasons why she might have done this. To appease the child? To make herself feel better about how the child looks? To get your husband's goat (I wish it weren't so, but some separated spouses do make decisions based on what will make their ex angry, using the child as some kind of "payback" for the strain of the divorce)? To show her off to others? You know what happened, but listening to why will help you get a picture of what this mother's struggles and concerns are. Then, you can speak to her issues, rather than from your upset about what happened.

If your husband wants to set a limit on actions like this, the limit will have a better chance of being thoughtfully received if you, or you and he, have listened to his ex first. You want to set up a tradition where the three of you sit down and talk about how parenting is going for each of you, about the concerns you each have, and the ideas you each have, so that the well being of the  child is clearly at the center of your efforts. In this context, you can listen first, then make a request that will be better heard.