He said that his eldest sister was better than his daughter-in-law, and he felt particularly uncomfortable. What can you say to express me?

Calm the daughter-in-law, make her happy first, and then find the right opportunity to communicate with her mother and sister. First, let your daughter-in-law communicate with them more and buy some small gifts to ease the atmosphere. Then you can tell your mother and sister that your daughter-in-law cares about them, speak well of them, and ask them to take care of her and be kind to her. You are the best adhesive. Come on, as long as you work hard, your big family will be very harmonious and warm. Good luck!