Is it permissible for an uncle (over bar mitzvah) to babysit his 2 nieces and nephew at night? Details: girl 1-age 8, girl 2-age 6, boy-age 4. They all go to sleep (or are already in bed/sleeping) except for the oldest girl, who stays up for awhile until she goes to sleep. No one else is home. In an apartment building.
Thank you very much!
A boy over the age of 13 may not babysit for a girl aged 8 unless there are shomrim or other factors which serve to permit Yichud (see Even Ha-Ezer 22:1, 11).
A girl age six is considered a shomer, but at night two shomrim are required, and a boy aged four will not generally be considered a shomer (he is not old enough to be aware of improper conduct and report on to others).
Therefore, additional arrangements should be made. The best arrangement is that a key should be given to a neighbor, and it should be agreed that he can drop in at any time. This will be sufficient to permit the situation.