J.R.
Hi S. (very pretty name by the way... )
I don't think there is anything you can do. Offer advice when she asks for it.
My SIL lets her son walk all over her - she caters to his every whim, and he's a ROTTEN BRAT - I love the kid don't get me wrong, but he is so beyond spoiled it's not even funny (he has an ATV and one of those mini motorcycles, the entire basement is his playroom, he has a friggin roller coaster down there and every other toy imaginable, he doesn't listen and he's mean to other kids...). All I can do is give her my opinion if she asks for it and keep my mouth shut otherwise. I know I don't like being told what to do... with unsolicited advice... so i try my best to 'do onto others as i would have done to me'...
let her doctor yell at her for it... or the dentist :)