I think the mystery of Johanna Margaretha is solved!
I found her on the passenger list of the SS Amsterdam, dep Amsterdam, arr NY 10 Mar 1884.https://familysearch.org/ark:/61903/3:1:939V-519J-VB?i=1031&...
Her name is transcribed as Johanna Staffe.
She is the second last on the list and there is a bad paper fold through her name. But if you enlarge it, you can make out the name Johanna Stuffer.....
She arrived just 12 days before her marriage to Arie, so either they knew each other already in The Netherlands, or it was an arranged marriage.
In the 1900 census it is stated that she is born in April 1850. Now the year can be off by one or so, but the month is usually correct.
There is a national database in The Netherlands where most of the marriages are to be found. Births and deaths are not always included, so I looked at the places of marriage for the name Stuffers. Then I looked at the places which did not have the birth registrations included in this database. Haarlem was one of them (births after 1844). Then I searched through familysearch.org for births in Haarlem. And I found her!!!!
Johanna Margaretha Stuffers
Born Haarlem 18 Apr 1850
Daughter of Abraham Gerardus Stuffers (shop keeper) and Margaretha van den Berghttps://familysearch.org/search/collection/results?count=75&...
top left hand page
If the parents' names on the marriage license correspond with the names I just gave, you are sure.
I really don't have any doubt that this is the correct Johanna Margaretha, but it is always better to have proof.