If you really want to know what happened to Rick, who is from Robotech and has his own continuity separate from Hikaru, I recommend the unfinished/canceled
"Robotech II: The Sentinels" series (the first few episodes of which are collected into an official dvd movie) and then follow-up by reading the 5-book novelization of Robotech: The Sentinels, and its sequel*, by Jack McKinney. (Books: The Devil's Hand, Dark Powers, Death Dance, World Killers, Rubicon, and *End of the Circle).
The Shadow Chronicles was an attempt to erase/recon the previous books and movie, but it didn't turn out any better in my mind. Shadow Chronicles was pretty mediocre at best, and didn't sit right with me. Despite its flaws, I prefer the direction of The Sentinels as a RT sequel. And it covers not only Rick, but Lisa and the others, as well.http://en.wikipedia.org/wiki/Robotech_II:_The_Sentinelshttp://www.robotech.com/infopedia/bibliography/novels/
(scroll down for Sentinels book covers/ISBNs)