https://tvline.com/2019/03/29/david-james-elliott-jag-ncis-la-season-10-harm/

The May 12 episode of the CBS drama will mark the first time that Elliott will play his JAG role of Navy Captain Harmon Rabb Jr. on an NCIS series. He'll appear in multiple episodes of NCIS: Los Angeles, a spinoff of NCIS, which is a spinoff of JAG. Elliott originally played Rabb during JAG's run from 1995 to 2005. “Bringing Harmon Rabb to work with (the Los Angeles NCIS team) makes for a formidable coalition,” says NCIS: Los Angeles showrunner R. Scott Gemmill, “and both entities are going to need all the help they can get when confronted with the greatest challenge of their careers.” Gemmill says a major goal of his to reunite Elliott with original JAG star Catherine Bell, who also hasn't appeared on any of the NCIS shows.

My mistake.

Catherine Bell will join David James Elliott in reprising their JAG roles on NCIS: Los Angeles (https://ew.com/tv/2019/04/02/catherine-bell-reprise-jag-role-ncis-los-angeles/)

Four days after it was announced Elliott will reprise his role as Capt. Harmon Rabb Jr., the NCIS spinoff has booked Bell to reprise her role as Lt. Col. Sarah “Mac” MacKenzie for the May 19 NCIS: Los Angeles season finale. Elliott will reprise his role as part of a multi-episode arc beginning with the May 12 episode. “Catherine’s Mac was a strong, smart woman who held her own, and then some, in a male-dominated world," NCIS: Los Angeles showrunner R. Scott Gemmill said in a statement. "Her character paved the way for other strong female leads. Not only is it great to be working together again as friends, but to be able to write for Catherine and have her same character interact with our NCIS: Los Angeles characters now, that’s wonderfully surreal. It feels like everything has come full circle.”

That is cool.

Here's your first look at David James Elliott reprising his JAG role on NCIS: Los Angeles (https://ew.com/tv/2019/04/11/ncis-la-david-james-elliott-first-look/)

Elliott, who played Navy Capt. Harmon Rabb Jr. on JAG from 1995 to 2005, will first appear on the CBS drama -- a spinoff of JAG spinoff NCIS -- on May 12.