An Askan went to the Vilna Gaon and told him he saw a Chassid eating on Tshia B’av with a female on his lap.
The Vilna Gaon then declared Chassdim Apikorsus and put them in Cherem.
The Askan DID NOT tell the Vilna Gaon the the Female was his grandaughter and it was Shabbos Tsha B’av (When eating is permitted)