That boy was my soon-to-be stepbrother, Richard, who I'd been. to keep a step- brother and sister apart at night and had to stop family
Question about English (US) @kevinckho: Okay, so a step-brother/sister would be, Adam's mom gets married to Jeff and he has a daughter
A step-sibling is a sibling by marriage only - one of your parents has married one of Ralph is your step-brother; Grace is your half-sister.