I agree fully with ”falsterden” that the Thora connection was a miss. Having checked as much as I can (without being a paying member) on Ancestry and FamilySearch, it’s clear that transcription errors have mislead us.
I also tried in every possible way to find Bertel in the WW1 draft records but with no luck. So most likely he left the US within a few years.
Anyway, I learned yesterday that a very old family member (a nephew of the two brothers) is still around. I expect to be connected to him next week. Maybe he will remember if his father ever told about a “missing” brother Bertel.
If the old man verifies that Bertel stayed in the US I’ll revive the thread (and only then).