I'm so sorry I haven't replied to your post until now. This has been an exceptionally hectic year for me, so I just haven't had the time to check whether anyone had posted any further comments on my thread - also I didn't think anyone would have any more information about the Nyson twins or the family in general, as it seems there were no other children.
Here's a link to a Norwegian site where I posted a thread and received lots of interesting info (for me) on the family. Amongst other things you will see the birth records for the twins, and their full given names:http://www.disnorge.no/slektsforum/viewtopic.php?t=102858&am...
Hoping to hear from you again.