I enjoy a challenge like this, although I mostly find them and fix them on FamilySearch. The process should be the same though.
I wouldn't make any changes, except fixing the most obvious errors, until you have first gathered all the data you can find. You've identified some of the bad data and sources, and you've found a few good sources. I would continue your research into the Sarah's and people involved with her, until the moment you've gained a pretty good confidence in who is who, and what data belongs to each one. If you start fixing things too soon, you make mistakes, because your picture of each is too incomplete, and that makes it too easy to jump to the wrong conclusions. Finding additional sources makes finding the right conclusions easier.
But sometimes, especially that far back, it may be hard to find more sources, and you have to make the best of what you've got. Then it's a matter of determining what facts are credible and consistent, and what facts are not, are inconsistent with the credible ones. We make profiles based on what's credible, hopefully documented. We make research notes about the rest.
I wish you the best in this, and hope you find the fun and satisfaction of untangling terrible tangles like this.