Dragon's Time by Anne McCaffrey and Todd McCaffrey
The introduction by Anne says the book after this one is Dragonrider, but I don't know if Todd has enough info to do that without her.
This is actually a gathering together of lost or left-out parts from the earlier books with Anne and Todd, and only a small bit of new material. There's polyamory, time travel, and clairvoyance. It's not a wonderful book, but it does clean things up a bit.
You should read it only if you really like Pern books.
