The assassin who works for Terror is called Abihira Rah, real last name Sinistrah. Chapter 16 reveals that David's original name is Lucius Sinistrah, Jr. Is Sinistrah a common surname on Vampiru, or are they related?
Abihira can read David's mind. Maybe that's proof that they're related.
Chapter 19 reveals that they're brother and sister.
At the end of chapter 19, Dani is called a "traitor to the human race". Why? Because she told Edward about InGEN, and Edward works for Terror...
Nightmare got the idea for her army of zombies, made from the remains of aborted babies from Terror. That means that Terror has at least thought of doing what Nightmare is doing.