Maynard, I remember seeing a reference, not sure where, to a Herbert Threlkeld-Edwards, born the same timeframe you mention. I recall it because the hyphenated surname was unusual for the era, and because the location was also unusual for most Threlkelds at the time. NY, PA, or MD, I think. But I've not looked into it further.
Please consider joining WikiTree. Collaboration and technology are how we can can dig deeper into our shared family tree. Once you join, send me a private message from my profile and I'll do what I can to help you determine Rhoda's line.
By the way, since my February post, we have a new article on the Threlkeld One-Name Study website by Jim Threlkeld, titled "Cumbria, a Forgotten Celtic Kingdom." It might be of interest.