The first indication that Hailey would be able to use the diapers safely was that the only time her parents would see Erin wet was if Erin went downstairs for breakfast in a soggy diaper and thin pajamas that were unable to hide it. Otherwise, her parents had no other opportunity. The diapers were thrown away in the same container whether they were wet or dry, and her mother didn’t check the container, as it was the girls’ responsibility to empty it.
The rate at which her parents had to buy new diapers was unlikely to be a problem, if she was careful. Even if Erin was dry, the two girls used two diapers per night between them; if Erin woke up wet in the middle of the night, there was a third.