How do Okonkwo's wives relate in Things Fall Apart?

None of Okonkwo's wives are said to relate to each other lineage-wise. They appear to be respectful to each other and cover for each other.

Their relationship is not really expounded upon save for the time when the first wife covers for Ojiugo's negligence as she gets her hair plaited during the week of Peace. The first wife also sees Ekwefi's unhappiness at the birth of the first wife's third son as malevolence, thought it was inward bitterness.