Commodore Decker's son, William, is featured in
Star Trek: The Motion Picture. Although never revealed on-screen, Gene Roddenberry's novelization of the movie makes this clear.
When they beam aboard the Constellation they head off to Auxiliary Control. Then we see Kirk walk past a room, turn, and see Decker inside. The room is apparently...Auxiliary Control. so why did Kirk walk past it - didn't he know where it was?
It seems odd that McCoy can't immediately certify Decker as unfit for command in the middle of a crisis situation, but must conduct a "battery of tests" as Spock says. In other episodes such as "Obsession" the ship's Chief Medical Officer clearly has the authority to certify the captain as unfit without a series of tests, and Decker is certainly acting shocked and distraught.
First appearance of another Constitution-class starship
other than the Enterprise.
First time the Enterprise encounters another
Consititution-class ship and finds the entire crew dead. A
similar situation occurs in
"The Omega Glory" and
"The Tholian Web".
Commodore Matt Decker was the father of Captain Willard
Decker, who rose to command of the Enterprise on the
recommendation of James Kirk in
Trek: The Motion Picture."
one counts the fan-made series "Star Trek: New Voyages" as
canonical, then Commodore Decker survived his suicide run at
the doomsday machine and was transported back in time to the
20th century as revealed in the episode "In Harm's Way."