I feel for your sister. Never had bedbugs, but when I was younger I got headlice (I almost want to say I got it twice). Which that in itself is horrible. But I remember after my headlice had cleared up I stayed with my grandma (who's more like a bad MIL than a grandma) and some other relatives at this beach house. A few days after leaving the beach house it was discovered one of the other kids had headlice. And immediatly my grandma thought "Well, she MUST have gotten it from Samantha!" and didn't even consider the idea that this kid got it elsewhere, possibly before staying at the beach house. I felt so horrible!