We never meet Miss Grantley, but she must be a debutante among the ton. Caroline Bingley asks Darcy to put in his letter to his sister that she is "quite in raptures with [Georgiana's] beautiful little design for a table, and [she] think[s] it infinitely superior to Miss Grantley's."
Given that the Darcys and the Bingleys both seem to know Miss Grantley, she likely has spent a fair amount of time in town but is likely not quite the level of the bigger Fitzwilliam family.
