Who is Reverend Mother Lucilla from Heretics of Dune and what is their importance?

Reverend Mother Lucilla is a trained Bene Gesserit "Imprinter," Lucilla is sent by the Reverend Mother Alma Mavis Taraza to the planet Gammu to take over training of the latest Duncan Idaho ghola from the skeptical old Reverend Mother Schwangyu. Lucilla is a brown-haired, large-breasted, motherly charmer who has already borne three children for the Sisterhood. Her mission is to teach Duncan "love in all of its forms" in preparation for turning him over to Senior Security Mother Darwi Odrade, who strikingly resembles Lucilla. Both are descendants of Siona Atreides. Lucilla depends on the Lady Jessica persona in Other Lives.