And here is a wild card lead:
Name: Author L. Cook
Event Type: Marriage
Event Date: 02 Sep 1883
Event Place: Montague County, Texas, United States
Spouse's Name: Tulla L. Price
GS Film Number: 001024888
Digital Folder Number: 005706851
Image Number: 00064
Citing this Record
"Texas, County Marriage Index, 1837-1977," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:QK8B-622S : 22 December 2016), Author L. Cook and Tulla L. Price, 02 Sep 1883; citing Montague County, Texas, United States, county courthouses, Texas; FHL microfilm 1,024,888.
If this Author L Cook is Veda's Arthur Cook, and Tulla is some relative of Dora's (a possibility, since a few of her uncles spent some time in Texas), then maybe young Samuel is their orphan son who somehow fell to Dora to raise...it is a long shot, but could be worth investigating...otherwise, I'm not turning up very many Arthur Cooks in the right vicinity!