In real life, we can often see that some people prefer to take advantage of small things and like to instill this kind of education in children. If such people are their relatives, sometimes it is really embarrassing. If they refuse directly, it will be ugly. If they don't refuse, they will form a habit and can't say it. Therefore, this situation needs to be handled with caution.

I think you should communicate this situation with your husband first and see what his opinion is. If her husband hates this kind of thing, but he is too embarrassed to say no, then you can try to tell his sister-in-law politely first. If her sister-in-law asks her children to come to your house again, you can say that she is out on business or not at home, and find reasons to contact him several times to refuse. She should be able to understand you gradually. If you do, she will still come to your house, and you can try to find herself.

If the above methods can't be solved, you can let your husband communicate directly with his brother and let them solve it internally. It would be better this way. Although it hurts the harmony, it is not directly faced, and it is understandable to safeguard one's own interests.

However, if all the methods have been tried and there is still no improvement, then you should consider actively communicating with your sister-in-law and telling her what you think. You are defending your space and interests. If you use many methods, such relatives still push their luck, and there is no need to estimate each other's face. In China, we can't decide who our relatives are, but we have the right to defend ourselves. We can't encourage their greed. Although family ties are important, all of us must live in harmony.