I suspect that there is too little information here for us to help u. Why is she able to threaten u with problems over defomation of character and wasting social services time (which she can't do as anyone with concerns over a child is actually obliged to call social services, the law and other organisations are very strong on that, even if someone is really making false claims to cause harrassment) so I'd let any of those threats just wash over you.
Have u tried court mediation.., I'd have thought it wouldn't look terribly good for her if she creates more problems during mediation.
However, I know I'm gonna sound like I am preaching and I do know its hard.., but try and avoid retaliating against her behaviour. Whatever u do.., you know your daughter will suffer most of all.
Have u tried
http://www.fnf.org.uk...ACFV1d4wodGhqalA?????