Thank you all so much for all of your quick and informative responses. Wow! I'm really blown away by all of the good information.
I just finished looking at the Houliston family tree (on Helen Bearup) that was included in Monica's response above. That is absolutely amazing.
I know I need to confirm all of the information, but it provides a great starting point - and it looks like it's very well researched.
Again, many thanks!
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P.S. I have two other outstanding questions where I've run into a brick wall:
1. Elspeth Ker (married to John Paterson in Scotland, with a son named John Paterson who is my 4th g-grandfather)
2. Agnes Adamson (married to Charles Smith in Scotland, with a son named Charles Smith who is my 3rd g-grandfather)