I'm really good friends with this couple who are both poly. Danielle* was telling me about a conversation she had with her seven-year-old step-daughter Jenny* about her little boyfriend at school.
After asking whether he'd kissed her yet ("No, I can still run faster than him"), Danielle asked Jenny if her boyfriend had any other girlfriends. Jenny answered "yes, Lisa" and Danielle asked her what she thought of Lisa. Jenny said, "she's pretty nice, and she's funny too."
Danielle took this opportunity to give Jenny some poly-support: "Well, that's good. It's important to like your boyfriend's other girlfriends."
I thought it was cute
*Names changed to protect their identities