When McGee tasks Morgan Cade with keeping an eye on Yorka as he calls Gibbs (Mark Harmon), Yorka tries to make another run for it. While attempting to restrain him, Morgan is shot in the stomach. A hostage situation breaks out, on this the day of McGee’s children’s birth, and chaos ensues. Eventually things are sorted and all the bad guys are handled.
Meanwhile Delilah gives birth to twins who they name John, after McGee’s dad, and Morgan after, well, Morgan. And then we never saw them again… until Season 20 perhaps?
Source: https://www.distractify.com/p/mcgee-ncis-kids