We're going trhough something similar. Although the step-father doesn't talk to us (he was my husband's friend and next door neighbor, and they were both in the military, he used his rank to mess up with my husband's military career to the point that he had to resign after 15 years), but between he and her mother have told the girl that he is her dad, the mother has told the child that she has three fathers:
1. BIOLOGICAL FATHER - the man that she had sexual relation with.
2. LEGAL FATHER - my husband, just for child support
3. DADDY - her step-father who is the man that is there for her every day.
This has reachd to a point that my SD doesn't wan to use my husband's (her legal last name), but her step-dad's.
I'll recommend that if you have a lawyer, have him or her to write them a letter. If you don't, write it your self; very nice, polite but strong. In this web-site I found some good information that I forwarded to our lawyer in regards to PAS and how the lawyers can deal with that in court.
We've been in court now for 4 years, first in FL nad now in CA. The judges and the courts are really lazy in regards to "the best interest of the children". I'm so sick and tired of listening to the judges telling the mother that she can not do this or that and she keeps doing it, and they keep giving her a chance to change and we have to stop that, because when the court come to child dupport, they don't have any pitty for the father regardless the situation he or his family is going through.
I wrote a letter to Dt. Phill's show. I'll tell you to do the same thing because if we don't make some noises, nobody else is going to do it for our children. This is hurting our children and us and we can't no longer sit down and wait until they grow up...it's going to be too late by then.
Also, there's a thread here in the VISITATION forum called HELP CHANGE THE CURRENT LAWS. Let's gather our voices and let's make a difference in this country.
PAS HAS TO BE TAKEN MORE SIRIOUSLY IN OURT COURT SYSTEM.
God bless you and your kids, and I'll be praying for you all.
Good luck and Happy Holidays!!!