Fauntleroy’s comment to Zenobia that she must be like a sister to Priscilla if she wants to keep her wealth is both a threat and a revelation. Because Zenobia’s uncle has died, Fauntleroy actually has a superior legal claim on his wealth (Zenobia’s inheritance) than she does. If she’s not nice to Priscilla, Fauntleroy can rightfully claim the money (although Zenobia might not quire realize this in the moment). The threat also reveals that the two are sisters. This makes it look extra suspicious that, on this same night, Priscilla seems to disappear. Or, as Coverdale notes, Zenobia might have thrown her away to protect both her relationship with Hollingsworth and her wealth.