Ok, here's the chronology in case anyone's interested:
- Received encore res.# via email, but did not show up in my account.
- Called encore desk back. They said MR was attached and it would show up (it never did)
- Called elite reservations line and they said they couldn't add it, only encore desk could
- Called encore desk back, new person said MR# could NOT be added on an encore res.
- Saw Bnov's post so called elite reservations line again, and Bam!, they added it.
So just like with II exchanges, the usual advice continues. Just keep calling till you find someone to add it.