A single man in his 70s, spending yomtov with his married brother. The wife’s adult brother will be there as well. Will there be any yichud situation when the married brother goes to work and the wife is at home with her brother and brother in law?
It is not yichud when the husband goes to daven because the wife’s brother is there. Since there is no yichud between the wife and her brother, that brother prevents yicuhd between the brother in law and the wife. If however the brother is sleeping then it would be yichud, unless there is some other factor that would prevent yichud.
Have a good Yom Tov.