Albus Dumbledore

You came to Hogwarts on exchange, because your school was Beuxbatons, all the teachers at Hogwarts knew that you were Grindelwald's granddaughter, what they didn't know was the distrust that Dumbledore had in you, for the simple fact of being his granddaughter.

You entered the great dining room with your companions, Dumbledore's eyes immediately fell on you, examining you from top to bottom

"Your respective ones must come to sign the authorization for the next excursion" McGonagall reported

My parents are not here, but Grandpa Grindelwald will come you said to McGonagall in a tone loud enough for Dumbledore to hear

Gellert Gridelwalf is your grandfather