916. Making an Eiruv or Shittuf Unilaterally
Eiruvin 1:19
The participants of a shittuf for an alley must also make an eiruv in their own courtyards. This is required so that their children will be aware of the concept of eiruv. Therefore, if bread is used to make a shittuf, the residents need not make an eiruv for the courtyards because the children will be aware of the bread. If a group of people were having a feast together when Shabbos arrived, they may rely on the bread on the table for use as their courtyard’s eiruv. They may also elect to use this bread as a shittuf for their alley even though they were dining in a courtyard.
Eiruvin 1:20
One of the residents of a courtyard may take bread and declare that it is intended for all the residents of his courtyard, or he may take a volume of food sufficient for two meals and declare that it is intended for all the residents of his alley. In such a case, one need not collect food from each resident. He must, however, give this food to another person, who will acquire it on behalf of the other residents. One’s adult son or daughter, Jewish servant or wife may acquire it on behalf of the other residents. A minor son or daughter and a Canaanite servant may not do so because they are not financially independent. A Jewish maidservant may accept it on behalf of the other residents even though she is below the age of majority; this is because a minor may take possession of something on behalf of others in matters that are required by Rabbinic law. One need not inform the residents of an alley or a courtyard that he performed this duty on their behalf because these things are for their benefit and one person may provide a benefit for another even without his knowledge.