Why can this not be translated as "Are they boys with their father?"
Because of "hos," which implies a place (like "jeg sover hos dig"--I sleep with you [at your place]")
I think the sentence does not tell whether the father is present. Someone please correct if I'm wrong on this.
How do you use hos? I've legitimately never seen this word until this sentence and haven't been taught it at all. I'm at numbers skill right now.
'Are the boys at their father's?' should also be accepted
This sentence is weird, it needs to be changed.
No it's not, it's a perfectly sane sentence. Which is more than can be said for many of the sentences that come up on this...
It apparently is accepted now, as thats the answer I gave