Lucrezia has some stories like this. The one here, The Second Sister (which is excellent) is somewhat along these lines. Others are for more mature audiences, so they are at other sites. It appears the author's main website is gone, so I suspect she has stopped writing, and perhaps even passed away. Another is The Strange Disappearance of Elizabeth Bennet (at least that's the best recollection I have of the title); it's rather violent in parts, but I expect you will fine the characters Jane, Mr and Mrs Bennet, and Mr Collins are all more than bad enough.
