Ah, Jane, I take your place now, and you must go lower, because I am a married woman
Traditionally your rank in life stated where you sat at the dinner table. Since Lydia was the first Bennet daughter to be married, she took Jane's spot on her father's right. A married women came before the eldest daughters and the older daughter was superior than the younger children in rank. (John Trusler, The Honours of the Table, 4)