[Mithalwen]

"Can I / someone else write / complete / develop my / their own version of one of these unfinished tales ? (or any others)
The simple answer is NO.
You are of course free to do whatever you like for your own private enjoyment, but there is no question of any commercial exploitation of this form of "fan-fiction".
Also, in these days of the Internet, and privately produced collectors’ items for sale on eBay, we must make it as clear as possible that the Tolkien Estate never has, and never will authorize the commercialisation or distribution of any works of this type.
The Estate exists to defend the integrity of J.R.R. Tolkien’s writings. Christopher Tolkien's work as his father’s literary executor has always been to publish as faithfully and honestly as possible his father's completed and uncompleted works, without adaptation or embellishment"