As Sir Thomas’ ward Fanny has the status of a gentlewoman but her consequence (rank) is less than that of his daughters. I feel when Sir Thomas said Fanny should be made to “remember that she is not a Miss Bertram” it was intended to be a kindness by discouraging expectations that could only be disappointed. He did not want her to grow-up expecting a grand marriage with all the amenities as her well bred, well connected and most likely well fortuned cousins have some right to expect. Sir Thomas was explicit that although the cousins could not be social equals he wanted them to be very good friends without arrogance on one side or I think a consciousness of personal inferiority on the other:

“There will be some difficulty in our way, Mrs. Norris,” observed Sir Thomas, “as to the distinction proper to be made between the girls as they grow up: how to preserve in the minds of my daughters the consciousness of what they are, without making them think too lowly of their cousin; and how, without depressing her spirits too far, to make her remember that she is not a Miss Bertram. I should wish to see them very good friends, and would, on no account, authorise in my girls the smallest degree of arrogance towards their relation; but still they cannot be equals. Their rank, fortune, rights, and expectations will always be different. It is a point of great delicacy, and you must assist us in our endeavours to choose exactly the right line of conduct.” (1)