Nothing wrong with that. Everyone has important people like that, even if it's just a few.

[ She mixes up the dry ingredients, now that they're all together. ]

My boyfriend has a younger brother. Their parents died when they were pretty young, so he's always had to look after him like a parent, especially while they've been here. I don't know if it's really the same, but I think that's the closest I've had to a sibling.