While digging around on the internet I found this:
Sanditon was Jane Austen's last, partially completed, novel of around 24,000 words, written between January 27th 1817 and March 18th 1817. Jane's niece Anna, the daughter of Jane's eldest brother James, had been brought up in her youngest years at Steventon with the 18 year older Jane, remained at Steventon with her father until she married Ben Lefroy at 21, and after a brief interlude moved back to Hampshire to live two miles away from Jane then living at Chawton.
Anna was surely the first 'Janeite' and harboured a life-long ambition to emulate and honour her aunt. In March 1845 she inherited Jane's manuscript in the will of Jane's sister Cassandra and set about writing her Completion, of similar length, and similarly unfinished.
In 2013 Chris Brindle, fascinated by the story behind the miniature of Anna Lefroy painted by his great great great grandfather acquired the original Lefroy Sanditon manuscripts from the USA and set about writing a stageplay based on the two fragments, with an ending that appeared a logical extension of the plot development in the Lefroy Continuation.