Another Mystery

James B. Cook married Ida M. Howard in 1880 in Iowa. 

They had two known children.  Floy, married to John Nickel and then Frank Yocum, and Merle.  Merle was married four times.  Nellie Morey was his first wife, Ella Neiman, was his second wife, number three was Mathilda Brunnier and finally Beatrice, last name unknown.  If he had any children, I am unaware of them.

While researching today I found another child, Greg Cook who was born in 1887 and apparently died before 1900 as he is not on the 1900 census.  His mother (Ida) is listed as the mother of three children, two alive. 

Also while researching today, I found a Marvel D. Cook, daughter of James and Ida married to Hubert W. Trent in 1920 in Iowa.  What is strange about her (my mystery) is that according to her marriage record she was born in Seattle.  She was born about 1901 and is not listed on the 1910 census with her parents.  Is she the daughter of my James Cook and Ida Howard?  Is there another James Cook married to an Ida Howard?  I find no record of the family ever in Seattle other than her marriage record.  Is the marriage record wrong?  I'm really starting to think she doesn't belong in our family as the 1910 census lists her mother as having three children, two alive.  Could she be an adopted daughter?  Adopted sometime between 1910 and 1920? 

Anyone out there know anything about this?  I would be grateful for any additional information on James and Ida (and family) along with any information about Marvel.