You're welcome sarring.
Why use Bohemia? It was Austria that ruled Bohemia, Moravia - present Czech Republic.

Up to 1918 it was Austria-Hungary with Hungary ruling present Slovak Republic. After the fall of this empire Czechoslovakia came to be www.cgsi.org - full map. [Ruthenia is now part of Ukraine. In 1995 Czechoslovakia separated into Czech Republic and Slovak Republic.

If they married in Gajary than Jakubov that is real close makes sense that one of them was from. Most of the time the marriage would take place in wife's church.
I have seen an US census where a Slovenian person is Slovak and vice a versa. I have seen an arrival manifest where a Moravian is listed as Bohemian.
What language did John SLEZAK list as "mother tongue" on an US census?

Since they married in "old country" than their church marriage record would have Helen's place of birth. The children's church baptismal record should have mother's maiden name.

Slezak, Helen 19 1900 1919
Slezak, John 32 1887 1919
I think this is the arrival manifest you are talking about.
Is there a typing error for Helen's age? Have you located their naturalization intent and petition? There would be some information maybe even Helen's maiden name.

I still say the ancestors were birds of a same feather - same language to communicate in and same tradition to observe.

Have you located John SLEZAK's first arrival to America?
Zlatica