I go through this once in awhile with my nuttyX. My child is younger than yours but we just say things like sometimes people say mean things when they are mad, or even if it hurts our feelings we know it's not true, or that it's ok for the child to let people know if they are saying things that hurt her feelings etc. I don't know what's gone on behind the scenes, but it's decreased over time. We just focus on how we feel or what we think about it, and don't engage in name calling back. At your child's age of 8 years old, this could be a good lesson learned about how sometimes people say things that just aren't very nice- and how to be Ok with knowing the truth themselves. There will come a time when the step-parent realizes (often too late) that they are only damaging their relationship with the child.