In The Giver, what did the family have to do in order for Gabriel to be allowed a second year of nurturing? (located in chapters 6-12)

The whole family had to sign contracts saying they wouldn't grow too attached to him if he continued to stay at their house in the evenings.  They had to say that they would willingly give him up the next year when it was time for him to be given to a "real" family at the naming ceremony.  This way, they would ensure he would be nurtured, but they weren't trying to break rules by getting a third child of their own.