This has been bandied about from time to time, I realize, but nothing happened in the v4 update so…Sibelius’s plugin was a charm; added slurs to melisma, (optionally) pointed out possible errors, and you could (optionally) highlight slurs so as to check your work. Something like this would be super duper!
Just to forestall arguments, I find that most singers want slurs, but if others on the forum have different experiences, fine. That’s why an optional rather than automatic feature would be great.