Isabella's mother married Balian of Ibelin in autumn 1177. His brother, Baldwin of Ibelin, wanted to marry Sybilla, but the king preferred another candidate, Guy of Lusignan. After the marriage of Sybilla and Guy on Easter 1180, a division emerged between Guy of Lusignan's supporters and opponents. The first group included the mother of Baldwin IV and Sybilla, Agnes of Courtenay, her brother, Joscelin, and Raynald of Châtillon, Lord of Oultrejordain. Their opponents included Isabella's mother and stepfather, and Raymond III of Tripoli. To secure Guy's position, the king arranged the betrothal of Isabella to Raynald of Châtillon's stepson, Humphrey IV of Toron in October 1180. Isabella was sent to Kerak Castle to be educated by Humphrey's mother, Stephanie of Milly. Stephanie forbade her to pay visits to her mother and stepfather at Nablus.