@TexasSpringBride: I can’t help thinking this will get buried under all the other messages you have here giving such great advice, but I wanted to just chip in.
I am a child of a mother who abandoned her children. When she left I was 6 years old. I now have relationship with my mother which I find satisfying and I no longer have any issues with the the fact she left. (This I consider to be very lucky, from a father who loved me completely and through a stint in therapy when I was in my early 20s)- in the 80’s you generally didn’t send a child to therapy so I can’t comment on the use of this.
Anyhow, when I was younger I used to lie about things, not necessarily as elborate as your SD but the same principle. I’d lie about where I was and where I’d been, I remember saying that the teachers didn’t let me eat my food at lunch time. I’d answer back in classes, I’d be sneaky about my lying so it almost came across as an innocent missunderstanding.
At the time I couldn’t explain why I was acting the way I was, it was as confusing to me as it was to everyone around me. At certain times I was as loving and sweet as the next child but then sometimes I just hit an emotional wall that I didn’t know how to cope with and I used to lash out by lying.
Many years later I now understand why I acted this way, it wasn’t to gain attention (although that helped) I was acting this way to see if people still cared about me, my thinking was, if my own mother didn’t want me, why does anyone else? Taking things away from me, grounding me and threatening me with punishment of any other kind didn’t work because I didn’t care about anything. I’d already lost the thing I loved the most.
I had no outlet that suited me to express my confused emotions, I wanted to inflict the pain I was feeling on other people so I would hurt them in similar ways to your SD.
The crunch for me was when, after one lying episode my father sat me down and said, I don’t care what you did, I don’t care that the teachers are mad, and that you’re in trouble, I care about you and I want to know what you need from me to fix this. It wasn’t a one off conversation but him getting on a level with me and telling me that my actions didn’t stop him loving me was what I needed to hear.
Rejection to a child is about the worse thing you can get, be it through abandoment or death, it makes you question the very purpose of your being. If the person who should love me the most can leave me, then so will eveyone else.
I don’t know if it a tact you’ve tried but helping your SD to understand WHY she’s lying rather than the fact that lying is wrong will help her express why she’s doing it. I’d encourge you to express – even if it sounds like its falling on deaf ears, that her mother leaving her wasn’t her fault, that her mother left because of X,y,z and that you love her and are so proud that she is a part of your family.
This is a huge area, and I’ve already gone on longer than I thought I would! But please feel free to PM me if you have anything you want to speak about more. I have a lot of empathy towards your stepdaughter, I’ve been there and I believe that under all the misdemeanour, with the right angle you can resolve this sooner than you think.