Quote 1
"She's ridiculous without being rich," Lavinia sniffed. (6.4)
Lavinia can't find enough bad things to say about Sara, even though she hardly knows her. Check out the fun way that Burnett makes Lavinia "sniff." Can't you just see her little nose stuck up in the air?
Quote 2
"I suppose she thinks she could be a princess if she was a beggar," said Lavinia. "Let us begin to call her Your Royal Highness." (6.13)
This whole "royal princess" thing kind of backfires on Lavinia when Sara takes it to mean that she should act like a princess in the generous and proper sense, not in the spoiled rotten sense.
Quote 3
"Perhaps the diamond mines have suddenly appeared again," said Lavinia, scathingly. "Don't please her by staring at her in that way, you silly thing." (16.83)
Oh, Lavinia. We would almost feel sorry for you, if you weren't such a waste of paper. (Just kidding. We need you around so we can see how much we like Sara.)