Quote Originally Posted by Inverarity
She contradicted herself in Tales of Beedle the Bard, which states that McGonagall did indeed become Headmistress.
Not exactly. She said McGonagall wasn't headmistress in 2017, but Beedle the Bard is earlier - 2008 - so McGonagall can be Headmistress without it being classed as a contradiction. She could have retired in 2015 when she was 90.

Molly- Mmm, I dislike the same teachers being there all the time as well as all the Trio's friends having children at the same time. How likely is it that Rose and Albus would go to school with a Thomas child, a Finnegan child and a Longbottom.