1,031. When Siblings Are Both Getting Married
145:25 The Sages said that a person should marry off his children close to puberty because if they are left unmarried, they will come to inappropriate behavior and thoughts. Regarding this, Job 5:24 says, "you shall visit your habitation and not sin."
Similarly, the Sages said that if a man sees that his wife isn't behaving in a proper manner and she has relationships with other men, he should rebuke her and warn her privately in a gentle way in order to remove this stumbling block and to lead her on the proper path. He should not tell her directly, "Don't be alone with so-and-so," not even in private. Since we no longer have the bitter waters to test a sotah, doing so could create a halachic quandary.
If a person isn't careful regarding his wife, his children and his household, warning them and supervising their ways until he knows that they are free from all sin, then he is a sinner as per Job 5:24, "You shall know that your tent will be in peace, you shall visit your habitation and not sin."
145:26 One may not make weddings for two brothers or two sisters (or a brother and a sister - Mishnah Brurah 546:1) on the same day because we don't mix one celebration with another. Some authorities say that we should not even do so in the same week. The proof for this is from our forefather Yaakov: Genesis 29:27 says, "fulfill the week of this one."