How would you handle this?

My 14 year old stepdaughter lives in another state with her mom, stepfather and half-siblings. She has half-siblings with us as well. My husband and his ex-wife are NOT on speaking terms. My step-daughter recently told her grandmother (my husband's mom) that they were traveling here for Thanksgiving (since both the mom and step-father are originally from the area where we still live).

My mother in law contacts my step-daughter's mom occasionally by email, just to be nice, ask for updated pictures, etc. About a month ago, the mom told my MIL that they changed their minds about coming up for Thanksgiving. We recently learned from a mutual friend that the mom's myspace page indicates that they really are coming here and that she probably lied to my MIL.

My stepdaughter hasn't said a thing about it to any of us, so we figure she must know her mom lied to us. But considering that they'd have traveled halfway across the country, don't you think the kid deserves to see the rest of HER family, too - considering she has grandparents AND 80, 90 and 100 year old great-grandparents?

Do we let it go, or call them out on it?