Oh, you have NO idea how familiar that story sounds to so many here! Too many here have BT, DT....even
DH and I, to a degree. Problem is, unless she becomes a threat to
SD's physical and emotional wellbeing (and you have the documentation to prove it), there's really nothing you can do about it. About the only thing you can do while SD is with her is to make sure SD knows how and when to dial 911 if she feels threatened. Or if SD were to ever call you (or you have a suspicion of something going on, illegal or otherwise that you feel is a physical threat to SD), then call local law enforcement and ask for a welfare check of the residence. They will go to the home to check and if they feel SD is in
imminent danger, they will remove SD from the premises.
Unfortunately, something practically has to happen in order for anything to change. Only then would you be able to open the issue up in family court. What you're currently doing......showing and teaching by example and teaching her to react differently........is about all you can do for the time being, and possibly for years.
As SD gets older, either she will show signs of increased mental instability (in that case, you would be justified in having her professionally evaluated) or she will learn that only
BM is the only who acts that way. My
SS will be 16 next month and has learned over the years that his BM's 'quirks' are not normal behavior compared to others and now sees it for what it is.........in his words 'Mom is just weird'.