Blood Sister is an examination of sibling rivalry, but is it thorough enough? Sibling rivalry can be a potent ingredient for drama because even though blood may be proverbially thicker than water, conflict is no respecter of relationships, especially in film.There’s naturally a lot for siblings to fight over — who gets the most attention from parents, who should eat the bigger piece of meat, and who gets not to do the dishes. With any luck, the rivalry means nothing more than squabbles that end as quickly as they start. Before she became Nollywood’s sweetheart, glowing with the air of industry…