Related Clues:

• What’s the most common feature of selfless relative?
• First roomie, often
• Short word for a relative
• Short sibling?
• Familial rival, for short
• Start of a cry that ends 'bah!'
• Auntie, to one's parent
• "___-boom-bah"
• Childhood roomie, often
• One you might squabble with in the back seat
• Hand-me-down source, for short
• Little sibling
• 10-Across sibling
• Family member (informal)
• 54-Across' sib