You may ask where is Mcgonagall in FB: CoG?

She was at Hogwarts with Dumbledore.

When is Mcgonagall in FB?

In 1927.

So I thought Why is Mcgonagoll in FB?

IDK, she said that she has worked at Hogwarts for 39 years (In OoTP)...

Then I thought Who was McGonagall in FB?

Maybe it's not Minerva. But turns out it was her father's name (who was a muggle)

So the question is How is McGonagall in FB?