That thought passed my mind too, but unlikely considering the instance where the bites occurred while the children were awake and outside playing. OP and their coworkers probably would have noticed her moving around the house in her sleep as well during the times they were keeping vigil if that were the case

EDIT: sleep deprived myself and forgot for a moment that of course they wouldn't have noticed since no instances occurred while they were keeping watch. The outside playing instance still applies though!