Here is what I can find
1. Dorothy was one of 4 children of William Hubberstey and Mary Eccles - married Dec 2, 1732. (So with Dorothy's father being William, a son called William would not be unusual)
2. Seems to have been the first to marry. I have her having 2 children with Edward Simpson - Maria Simpson July 29, 1763 and Gregorius Simpson April 1761. There may have been more children, but I have not seen any records. Marriage was July 5, 1760 (Gregorius being the name of Edward's father)
3. Her brother Robert married Feb 14, 1767 (to Mary Watson), and her sister Mary on Feb 11, 1767 (to John Wilcock).
4. William Hubberstey (1 above) was the son of Robert Hubberstey and Isabel Culcheth. I can't be sure on this because the records conflict, but I believe Robert's mother was named Dorothy. This might account for the fact that one of Robert's daughters was Dorothy and one of William's daughters was Dorothy. Along the same line my guess would be that Robert's father was named William.
5. The Hubbersteys lived at Sorbrose House in Samlesbury until very recently. My blog on Hubberstey history is ... http://more-greene.blogspot.ca/
6. The marriage (Dorothy and Edward) shows up in the Brindle Registers (where the priest always wrote Hubberstey as Huberche) on July 5, 1760 http://www.archive.org/stream/lancashireregist23unknuoft#pag...
7. A bit of contrary evidence (William as son of Edward and Dorothy) is that Dorothy was the godmother to the daughter of John Wilcock (and Elizabeth Hubberstey) in 1771, so if she had had a son in the same year you would expect it to have been in the same registers, but it is not. Also there was a daughter