My daughter still goes to daycare, and she is always dressed up in nice dresses. But I did tell the her daycare provider that she was not to care about her getting dirty. Of course, if the dress causes problem for her to play, then she would tell me! I don't care if she gets dirty, I don't mind about the dresses either as they need to be worn out!

My advice, let her play and get dirty! If it's a problem with mom, next time she wont dress her that way. If it's not a problem, then mom will continue dressing her that way!

Second advice: Ask the mom if she cares. Tell her that her daughter will get dirty. You see what she thinks!

Sarah