Assuming you have two or more children and the eldest is at least several years older and/or much more mature than the youngest, how much authority should the older sibling have over the other in a every day situation? (As in they're not baby sitting or in a temporary position of power of any kind)

Much - Elder child helps fully with raising the younger child, even given punishments are valid.

Some - Elder child helps fully with the same daily raising necessities, but punishments are not valid.

A little - Elder child helps out physically, but punishments are invalid and teachings are left entirely up to the parents.

None - Elder child is not given any responsibility for the younger sibling(s), and has no say in teachings/punishments.