Uncle wouldn't work if the locals were to get really suspicious. It means both Ethan and his sibling (Hana's parent) would have to have come from the gate. Pretty unlikely! It could get them out of a sticky spot as a very temporary measure, though, as it did back in chapter 10 -- but nothing more than that.

Oh, good point. Well, what about big brother, then? Obviously there's a big age difference, but it's far from implausible. I mean, between me and my brothers, there's an 8 and 10-year gap.