What is the main conflict in Oroonoko: An Authoritative Text, Historical Backgrounds, Criticism by Aphra Behn?

The play, "Oroonoko" is designed with two running plots that have very little connection. The first story introduced to the audience is that of the Welldon sisters, Charlotte and Lucy, who leave their home of London, England, and move to Surinam, West Indies, in search of husbands. Their husband-hunting has run dry in London and they move to the the English colony of Surinam for a fresh start. Since apparently women cannot purchase land in Surinam in 1695, Charlotte disguises herself as a man. This ruse leads to other dimensions, however, when a rich, old widow becomes smitten with Charlotte, who she thinks is a man. Having designs on the old woman's fortune, Charlotte plays along to a degree. When they "marry" Charlotte recruits a local, Jack Stanmore who has designs on the widow, to sneak in at night and have sex with the woman.