Possible Clues:

• Either Bush 43 daughter
• Kiefer Sutherland and Ashley Olsen each has one
• Jenna, to Barbara
• ''Identical'' sibling
• Mary-Kate, to Ashley
• She may be fraternal
• Crook keeps insurance for close relative
• Sibling born at the same time as another
• Princess Leia, to Luke Skywalker
• Artemis, to Apollo