Yes, when MC opened up their restaurant in the city later, she kept trying to teach the little sister how to cook. Her mind wasn't into it though. The only reason why she asked to be taught management and accounting was so that she could be at the front desk and serve the customers instead. This wasn't really due to laziness, but because WHO like to frequent the restaurant. MC and mother-in-law sometimes find her away from the front desk making long small talk with said "special customer."
She eventually found out that the scholar was crushing on MC and was jealous and somewhat resentful, but it was never to the level where she was harboring malicious thoughts and scheming terrible things. I don't think we have to worry about that? Maybe? From what I've read, scholar Wong was deeply in love with his new wife anyway. Anyway, the little sister voiced her discontent and said something along the line of "what is so good about MC anyway?" blah blah blah, to which her mother told her to know her place. She told her that the good life that they were living right now was due to MC, and without her they would still be living a miserable life back in the village.
About scholar Wong (OK, I know nobody's asking, but humor me). After several failed attempt to court and woo MC, the clock to scholar Wong's bachelordoom finally ran out. His family made had arranged for a marriage with a noble girl, and it wasn't something that he could easily refuse. He went to MC's restaurant telling MC about his situation, hoping that he would get a reaction out of MC. I think he was trying to gauge whether the MC has any feelings no matter how little towards him, and if she did, perhaps he still got a chance. He was utterly crushed by MC's complete perfunctory response. It was implied that after getting married, he pretty much engaged in hedonistic pleasures with his wife and neglected his studies. He really wasn't mentioned much from then onward. The only time he got mentioned was when the writer's doing a story about the little sister.