Tortellis, The

From Wikipedia:

The Tortellis is an American sitcom that aired from January to May 1987 on NBC. The first spin-off of Cheers, The Tortellis stars Dan Hedaya and Jean Kasem.

Synopsis:

Hedaya and Kasem had appeared on Cheers on several occasions as Nick and Loretta Tortelli, who were (respectively) Carla Tortelli's loutish ex-husband and Nick's cheerful, bubble-headed new trophy wife. The show co-stars Timothy Williams as Anthony Tortelli, Nick and Carla's teenage son, and Mandy Ingber as Annie Tortelli, Anthony's young bride, reprising their roles from Cheers.

At the beginning of the series, Loretta leaves Nick and moved to Las Vegas to live with her sensible, divorced sister Charlotte (played by Carlene Watkins), and Charlotte's young son Mark (Aaron Moffat). The series follows Nick as he moves to Las Vegas to try to reconcile with Loretta, vowing to change his sleazy, conniving ways in the process. Nick and Loretta tentatively get back together, and Nick sets up a TV repair business and tries to reform—not always successfully. Anthony and Annie follow Nick to Las Vegas, and all six characters lived in the same house.

After the show was canceled, all four Tortelli characters made return appearances on Cheers, where it was revealed that Nick's TV repair business went under, but that Nick and Loretta were still together (albeit somewhat shakily) and had presumably moved back to Boston.

The characters of Charlotte and Mark Cooper were never seen or even referred to on any episode of Cheers, either before or after The Tortellis' run.