How did the ghosts keep the baby?

In The Graveyard Book, the matter of "custody" of the baby is decided both by the willingness of Mrs. and Mr. Owens to take the child into their protection, as well as input from the rest of the "community," as it stands in the book.
When the baby unknowingly escapes from its own murder by getting out of its crib, leaving the house, and walking up the hill to a nearby graveyard, it is discovered by a female ghost named Mrs. Owens. She is immediately charmed by the child and calls her husband over to see it as well. As they talk, Mr. Owens sees the child's would-be killer, a man named Jack, and mistakes him for "the babe's family, come to bring him back to the loving bosom." However, his wife is skeptical, and her alarm grows when she and her husband notice a new ghost, saying "My baby! He is trying to harm my baby!" This is the ghost of the baby's newly-dead mother, who is unable to protect her child because she has not been buried in the graveyard and is still getting used to her new "existence." The woman asks Mrs. Owns to protect her son, and while this would be difficult, Mrs. Owens says "if we can, then we will" and immediately asks her husband if he will be a father to the child. He agrees to do so, and the ghost of the mother disappears.
As Jack approaches, Mrs. and Mr. Owens vanish along with the child. Shortly after, a man dressed in dark clothes approaches. This is caretaker of the graveyard, Silas. He escorts the man Jack out of the graveyard, locks the gate, and then goes over the hill to where a number of ghosts are having a meeting to decide what should be done with the child. In support of Mrs. Owens's claim, Silas says, "I firmly believe that is is for good—Mrs. Owens and her husband have taken this child under their protection," followed by volunteering himself as guardian, saying "I can leave the graveyard and return. I can bring him food" since the ghosts themselves are unable to leave. There is still a lot of opposition to the idea of the child being given "Freedom of the Graveyard," and the council dismisses Mrs. Owens. As they continue to deliberate, another strong voice approaches in the form of the Lady on the Grey. Her words carry a lot of weight among the dead, and when she says that "The dead should have charity," the matter is decided. Gaiman writes,

The debate was over and ended, and, without so much as a show of hands, had been decided. The child called No-body Owens would be given the Freedom of the Graveyard.