stinkbugger wrote:
Why not just ask her about it in a non-confrontational way?
"Hey, are you using any tricks to get all that stuff?" etc.
Then based on her response go the path you want.
Do you ever see the niece and her mother at the same time?
If so, next time you see them, you could say to the niece in front of her mom -- "I just love your Springfield! It's amazing! I especially like how you've designed your premium areas. . I've been wanting to get some of those myself, but they're so expensive. You're very talented! How much did you have to spend to get those?"
If you never see them together, then you could say the same thing to her individually. It would be interesting to hear what she says. (If she's smart, she'll say nothing, and might even drop you as a neighbor. MAYBE it will give her a few sleepless nights if she worries you'd mention anything to her mom, but I doubt it.)