How frustrating. The Olof Zacheus in Svenneby, I mean.
The farm name thing is how it worked in Norway, I'm not all that skilled with the Norwegian practices. Thy also used farm names in Dalarna in Sweden (somewhat differently) - but this isn't i nvolved here.
In Sweden it would just make SO much sense for a guy from Svenneby to adopt a name like Sven(d)berg when he moved out, particularly if he moved to a big town.
Older wives and births too soon after marriage. Well, these things may not be as uncommon as one would think.