Can a divorced woman with two teenage daughters, all of whom sleep on the second floor of the home, host a divorced man that they do not have any connection to, with his 12-year-old son, in their basement apartment? the house has a combination lock that other people know. There is also a separate entrance to the basement. is it a problem for the divorced man and his son to sleep there overnight.
It is not considered yichud. Although at night there is a need to have an extra person in order to avoid a yichud situation, (one man and two women) since you have three women and two men, which is two more people than yichud, it is permitted.
Rema E:H 22-5.