Joan, I have looked at this census record and speculated as you have that Sarah Dove might be David W. Sedberry's mother-in-law.
But your message sparked an idea. I'm showing Sarah Dove as Julia's mother, temporarily, in hopes that ancestry.com might come up with a hint or two that will shed some light on the matter. Best hope is to connect with someone who is working on Sarah's family and can help us out.
Thanks for the spark,
Glynn