You are a parent. Your kids come first over tennis or anything else. Why do you count on her in the first place? You need to renegotiate kid-time, with you taking 90% of it. It is getting to the point that she can only be trusted with a supervised visit, as she might ditch them somewhere to go do her thing. Personally, I think a 17 year old with a driver's license is more responsible than she is.
