A & B then got divorced, A married C and B married D.
C had Child 2 and D had Child 3 from their previous marriage.
Couple A&C and couple B&D now share childcare responsibilities of Child 1, 2 & 3 and often babysit them together.
So, while none of the three children shares blood, Child 2 & 3 have a common Step-sibling, Child 1.
Child 2 & Child 3 could be called each other's Antipodal Siblings.
"How are you and Jimmy related?"
"Well, we're Antipodal Siblings. Him and I share the same step-sibling, Lucy. Lucy is my step-sister cause her mom married my dad and Jimmy's step-sister cause her dad married his mom. We're one big blended family!"
"So how are you Andrew related to each other?"
"My dad married Mary's mom and Andrew's mom married Mary's dad after Mary's parents got divorced. So mary is my step-sibling and also Andrew's step-sibling. That makes me and Andrew Antipodal Siblings."
Cigarette: Northern slang for a cigarette, used oft by mashed up mancunian ravers becasue of the resemblance of a hot(electric)stove to the end of a lit cigarette. Originated circa 1991 in the early halcyon days of the rave culture; we speculate during a drug fuelled hallucination by said manc.
'fuck me noel, i am bolloxed, is that a ciggy in your mouth, or the stove from me 'nans kitchen'/
General use: 'Give us a stove you cunt'