I think the question is a little poorly worded - the "oldest" descendant of an immigrant is Jon Oddsson Bergmann - Bergmann is a German name and does not follow the Icelandic naming pattern (-son -dottir). You identified the right place in the tree that an immigrant entered anyway
But Jon's "Bergmann" ancestry could be his father, grandfather, mother (maybe?)
Can you spot the change to the tree that makes question 5 possible?
By assuming Sigurdur's spouse is absent, we can marry Gunnar to Rakel, giving them children Robert and Stefan. This info wasn't clear from the problem, but the only possible way to answer question 5 - one of Gunnar's children inherited his name and not Rakel's, which makes question 5 possible.
Cheers to everyone involved. I'm glad everyone is living their best lives.
Looking forward for the V Rising update tomorrow? Marski might join us, he's back on Steam today.