Must my husband's wives veil themselves from my five-year-old son?

The boy mentioned is young, and it is not obligatory to cover the face in his presence, as Allah Almighty says: "Or [of] children who have not yet attained awareness of the private aspects of women." This child has not yet attained awareness of the private aspects of women, so it is permissible to display one's adornment in front of him. Ibn Kathir explained this by saying that a young child does not understand the affairs of women and their private aspects, so there is no harm in him entering upon them. However, if he is an adolescent or close to it and understands these matters, he is not permitted to enter upon women.