What is the main conflict in The Memoirs of Cleopatra: A Novel by Margaret George?

Cleopatra attempts to remain out of sight of her sisters, hoping that she won't be killed for being a threat to them. The two young women are in control only a short time when the older is murdered by the younger. The younger then marries and prepares to be ruler, but Cleopatra's father overthrows her and Cleopatra is forced to watch as her sister is publicly executed. Cleopatra becomes co-ruler with her father and remains in that role until her father's death. Then her younger sister an