Did she get the court to agree to that custody setup? Not a father-friendly state? frown

The problem isn't really how this backtalking impacts you, but how it impacts the kids over time. You will probably not get an accurate representation from them of everything that was said. They will downplay it to you, or possibly use it for attention.

I've seen this exact scenario impact hundreds of divorced families over years. And I know how much you will hate it when your in-a-few-years teen daughters talk down to you in Ex's voice... Your reply to them already indicates that this is a problem, IMO.

She's probably not going to listen to you, but a co-parenting class has been very helpful to many. It's something about when it comes from a counselor...

M 16 yrs, WH62, P54
3 adult blended kids
EA 11/13, BD1 6/14
PA fall 14, BD2 2/15
Piecing 2015, BD3 12/15
Separated 4/16
WH moved OW in 5/16
Divorced 6/15/17