DD is 4 and now attends pre-school nursery every afternoon. She has recently become "bestfriends" with another girl who to be perfectly honest I would rather she didn't play with. This other child's behaviour is disruptive, most days she has to go and sit on the naughty chair. She has bitten dd twice, yesterday she pushed another child over and tore a brand new book. DD plays with her almost exclusively and she is starting to say and do things. WHen I question her about where she learnt those words etc she replies "from * (girl's name)".
I don't want to over react about this, but as a general rule dd is pretty well behaved and I don't want this to be spoilt by bad influences.
How would you deal with this situation?