I haven't yet found what I'm looking for, but you may be able to help me with this as living in US and maybe able to look into data and registrations I can not.
First let me help you with your Dutch history.
Helen Datema was born as Hiltje Datema at the village of Ezinge, Aduard on 05-07-1878. She was a daughter of Lucas / Lukas Datema (1843-1908) and Grietje Drent(h)je (1850-19..). They married at Ezinge, Aduard 09-07-1874. Lucas Datema was the son of Gerrit Pieters Datema and Janke Harms Sijtzema. Grietje Drentje was a daughter of Jakob Jakobs Drentje and Hiltje Gerrits Sasveld.
I found several children Datema. Janke (f) 1876-1939 married twice, Hiltje 1878-1948, Jakob 1881-19.. married 1906 Marigje Alijda van Bottenburg, Gerrit 1883-1901, Pieter (m) 1886-1887, Pieterke (f) 1888-19.., Aaltje (f) 1891- ....
Are you related to Jakob ??
Hiltje Datema must have known Jan (John) Mennes already in The Netherlands, because she came to Jan Mennes in Kalamazoo early 1908 and they married 03-06-1908 (june third - I use European notation - pretty confusing).
Daughter Grace was born 1909, no further information on her.
Son Albert was born 07-09-1910, married Evelyn June Nash (1916-1988). Their son Albert W. was born 18-10-1937 and died (62) Vicksburg 08-03-1999. Children ??
Son Lucas or Luke was born 14-06-1912 and died (87) Schoolcraft Kalamazoo 15-04-1999. Children ??
Daughter Emma was born 1915 ?? No further info on her.
Son Garrett was born 04-03-1916 and died (58) sept. 1974. He married Helen ..... (1914-?). They had a daughter Gertrude 1938 ??
And there was a stillborn daughter Ida 15-05-1920.
Maybe you could help to get me in an email contact with any (grand)grandchildren of John Mennes and Helen Datema; I don't have the means to find any.
Roosendaak The Netherlands