Thank you for your response! I was eyeing that Levi Castle as a good candidate for Rebecca's father. However, I noted that many family trees posted on-line have this Levi married to an Olive Bronson. I do not know the source of this information. Nobody mentions another wife or a child named Rebecca.
Rebecca was probably born in the early 1780s, since her husband William Russell Williams was born in about 1783 and their marriage was in Watertown in 1804, according to my chart. It's not clear that the Levi Castle who was b. in 1747 could have had a child by another wife in this time period. Perhaps somebody who has more information about him could comment. Perhaps there was another Levi Castle in CT during this time period. I'm not sure the Levi on my chart who supposedly m. Lola/Loly Andrus was b. in Waterbury.