[Mithalwen]

Well clearly they licensed the musical (it says so in the programme apart form anything else), the LOTR character names are their trademarks which is largely protecting merchandise (though what attraction those creepy dolls that resemble the actors only enough to disturb is I don't know - they must make some money on them beofre they end up in TK maxx).

The main implication for any hypothetical film based on the other works would be that they wouldn't be able to call Elrond (and presumably Glorfindel)
Elrond and Glorfindel without the permission of T-Enterprises and coughing up the money. Tyoical that these are among the few characters in the whole shebang with just the one name.... I don't think you can trade mark dictionary words so they could probably use Blue Mountains and so forth butmaybe not Rivendell.

Now that I think of it I recall that the Elf who fulfilled the the role of Gildor wasn't called Gildor in the musical but Elranien(wandering elf) - which may suggest that not all the names are trademarked.