once the deceased son had a wife, the family could adopt an heir, or a "grandson", to continue on the family line. the purpose of the daughter-in-law was not to produce offspring, as she was to live a chaste life, but she became the "social instrument" to enable the family to adopt. the family preferred to adopt patrilineally related male kin, usually through a brother assigning one of his own sons to the lineage of the deceased. the adoption was carried out by writing up a contract, which was then placed under the dead man's tablet. as an adopted son, his duties were to make ancestral offerings on his birth and death dates, and he was additionally "entitled to inherit his foster father's share of the family estate."