WMG / Island Beneath the Sea

Maurice Valmorain the elder was Violette's biological father

Zarité's children by Toulouse Valmorain are mentioned to strongly resemble Violette a few times. While this could just be symbolic and/or chalked up to coincidence, it's not impossible that there could be an actual blood tie that would account for the resemblance. Violette does seem to be unaware of (and uninterested in) her biological father's identity (the officer who killed her mother being only a possible candidate), and we do know Maurice had been living in Haiti for quite a few years prior to the events of the novel, meaning the timeline could line up.