A few points: The "Almanak" of 1914 mentions that Eiríkurs widow and their two children are living in Minnesota at that time.
Sigurður was on a ship that stranded in 1880. He emigrated in 1882, and the last I know of him is that he was in Alberta in 1914.He was married to Soffía Sigurðardóttir and they had at least one son, named Sigfinnur.
Gróa married Guðmundur Magnússon and died in 1887.They had 6 children and two of those have descendants in Iceland.
I am not aware of any Steingrímur - I suspect it is an error.