I agree with Pain18. I too would have little time for gossiping in-laws who are only interested in talking to me when I have something of value they need.
I wouldn't avoid her entirely though or pass messages through W or FIL. Things get lost or exaggerated in translation.
If and when SIL tries to call you back, don't pick up, but send her back a text (after an appropriate time) along the lines of "Hi - got your message. I am sorry I am not able to help you. I am not licensed in your state. I suggest contacting [some random enquiry number or website] if you need advice in this area". She won't contact you again. Your IL's will probably have a field day at your expense but f' em.
Also, who gets their dad to call on their behalf? Are these people not adults ?
