I had one like that. The issue I had is that often she would be very hurt if I suggested she went off and played with the other children (she'd say "they're my friends too") and she then didn't make the children friendships. It was very difficult to manage as socially she wasn't confident, but she wasn't helping herself by this.
She would have been about 9yo when I sat her down after one such time and discussed a few social rules.
What had happened was I had a friend and I was telling a short story about something that had happened a couple of weeks ago that I knew my friend would find interesting. In the way that you do, I shortened it a bit to keep it brief. DD interrupted with "but mummy it didn't happen like that. It was two weeks ago last Thursday, not Wednesday and it wasn't raining when we got up and it was A who said to B then C got involved... or was it D..."
She was correct. That was precisely how it happened. BUT it was totally irrelevant to the story and it changed the story so much the point was lost.
So I explained how she would feel uncomfortable when she was with her friends if I sat in with them and wanted to talk to them all the time.
We also did an exercise when I got her to reduce a story down to as few words as possible keeping the meaning. It helped her see that it didn't matter if it happened on Thursday or Wednesday or any other day! That meant when she came to talk she didn't go into one of those children's long rambly stories that never seems to come to a conclusion!
We also agreed that she could stay and say hello, and stay for a little while, but then had to go off. We agreed that she was better to go and join in with the other children at the beginning, but she could come back to me for a quick break.
We also discussed about taking a break from the other children. Rather than walking off and just leaving them, saying she needed a drink or wanted to ask me something made it easier for her to go back. Then when she came to me rather than settling down and joining in a conversation she would offer to make another drink or fetch biscuits, which gave her a job then she felt important.
It did work, and she grew into her character as she grew older. She now knows there are times I want to catch up with my friends, and there's times she is welcome to join us.