For the past 6 months, dd (14) has been smearing what I now think might be make-up over the mirrors in the house. I've asked her about it (she denies) and I've got her to clean them (she does it grumpily). It is definitely her. She has some slight tics which appear every now and then. I have no idea how to manage the smearing. She's doing really well at school both academically and in sport and has a good group of friends. We have a reasonably good relationship (along with the typical teenage tantrums we hug and say we love each other regularly). Has anyone had any experience of this at all?