Possible Clues:

• Some family members, for short
• Twins, e.g., for short
• Brothers and sisters, briefly
• Some family members, informally
• Sasha and Malia, e.g
• Twins, e.g., briefly
• A boy and his sis, e.g
• Ones sharing a branch of a tree
• Pair in bunk beds, perhaps
• Chloe and Halle Bailey, e.g., for short