If your DC has achieved a grammar score then she hasn't scraped in she's passed. Many DC who also could easily cope with the standard of work just miss out on a place by a couple of points. Many DC miss out by more than a couple and get through on appeal and cruise through Grammar. This scraping in is a modern day myth that nobody ever thought about in the days when neither scores or ranks were given out.
I have also experienced this with my own DC. The DC who passed with the lower score coped far better than the one with the much higher score. There are all sorts of reasons that DC don't cope at Grammar school (and Comprehensives) and it has nothing to do with how they score on a one off test.
Well done to your DD, enjoy her achievement