DD2 is 12, in year 8.
There is a girl in her class who she was good friends with from year 3. They would sometimes fall out, then make up friends, as people do.
However, particularly since they have been in the senior school, things have become quite unpleasant between them.
The girl (X) began to ignore DD, for no apparent reason, for weeks at a time. While this was happening, she would also encourage others in the friendship group to ignore DD.
After a while, she would decide to be friends. She would give her reasons for the falling out to be things like "I'm sorry, I was in a bad mood, and I took it out on you." or "I called you in the corridor, but you didn't answer, so I thought you were ignoring me" (DD had not heard her call.) At first DD was happy to make friends with her, but she soon got tired of the cycle, and stopped wanting to be friends with her. Then X would involve all their other friends and DD would feel very pressurised into making up, only to be subject to the same silent treatment a few weeks later.
As DD became more resolute in not wanting to make up friends again, X started to involve the rest of the class in pressurising DD to be friends with her. At least once, she had the form teacher involved in "peacemaking". (The next time it happened, I emailed the teacher to ask her, politely, to stay out of it, on DD's request.)
X makes things very difficult for DD, when she is ignoring her. She will say nasty things about her to other friends. If DD is chatting to someone, X will call them away, to speak to them "urgently".
It seems like, not content to ostrasize DD herself, she wants to encourage the rest of the girls to do so.
Recently, she has really ramped up the situation, trying to get DD in to trouble. In one practical lesson, DD and her partner were next to X and her partner. They were a bit rowdy, and X told the teacher, who (rightly) told them off. But a couple of days later, X told the teacher that it had happened again, which was untrue. (DD had to go to the teacher to explain - luckily she was believed.)
So.
A couple of days ago, X's mother rang me to say that X had come out of school in tears, because DD had spread a rumour about her. I questioned DD, and she told me that she and three other girls had been joking between the four of them, that one of the four had had sex with X (a silly schoolgirl joke, although, I agree not fair to joke about X who wasn't there - I have spoken to DD about this).
Somehow, the joke spread beyond the four of them. DD did not spread it, and I think possibly it was overheard by someone else, who spread it as a rumour. The rumour was spread over the course of the afternoon, but no one spoke about it at all the following day. So, X had a very unpleasant afternoon.
DD sent a text to X apologising profusely about her part in the situation. X replied to the text demanding that DD go round to tell everyone she had spread the rumour to that it was not true. In fact, DD had not spread the rumour, so had no one to tell. And in any case, as DD pointed out, that would only dredge it up again, and be worse for X.
X has blamed only DD and does not apportion any blame to the other girls in the four. Further, she has told others (including one of the group of four "jokers") that DD's apology is not a proper apology.
So it seems to me that she is now using this as just one further thing to get at DD.
X's mother does not believe DD's version of events, even though X was not there at the time, and therefore could not have known how the rumour started. She was very upset and apalled at the nature of the joking. (Perhaps that was coloured by the fact that it had caused the horrible rumour though, rather than actually being offended by it, though, because I thought the joke quite tame, although not really amusing.)
So, my concern is this. That X will continue to try to ostracize DD from her friends, and make her school life very difficult. DD is low down the social pecking order in the class, anyway, and can't afford to lose friends, as she would find it hard to make new ones.
Should I speak to the school, or is it all too nebulous?