Konrad must have died or returned to Denmark, which would explain why no WW-1 draft registration.
And, evidently "Barnes" in the 1920 census was a very bad misspelling of Busch:
In 1930, Johanne was in Hoboken New Jersey with husband Einar Busch, their daughter Mildred Busch 11, Johanne's married daughter Margaret Bortmas 23, and daughter Edna 20 with husband Leo Brown and their daughter Johanne 8/12.
In 1940 Johanna Busch 62 is a widow back in New York with daughter Mildred Bucher 21, who is already a widow with son Edward 2.
(Could not get full page census images to attach)