Jan:
Thanks for your question and for your interest in WikiTree.
Have you seen this feature (page)? http://www.wikitree.com/genealogy/FELLMAN which lists all the Fellman surname profiles presently on WikiTree...
You might try contacting the profile managers of those pages via the Private message link on each of those profile pages and asking your question about Peter and Henrik Fellman that way. You will have a greater chance of getting the direct attention of one or more of them, (I believe), since not all contributors to WikiTree are active on G2G.
Thanks again, I hope this helps,
Keith