Private Secretary to The City

Lucy Ricardo was friends with Susan McNamera from Private Secretary

The Danny Thomas Show's Williams family shares a home (briefly) with the Ricardo family on The Lucy-Desi Comedy Hour in 1958, the next year the Ricardo family returned the favor and visited the Williams' on The Danny Thomas Show.

The Danny Thomas Show came back as Make Room For Granddaddy

Make Room for Grandaddy's Williams had Here's Lucy's Lucy Carter as a houseguest

Here's Lucy's Lucy Carter and Mannix's Mannix are held hostage in an episode of Here's Lucy.

Mannix returned to TV on an episode of Diagnosis Murder to solve an old unsolved case with the help of Dr Mark Sloan.

Diagnosis Murder's Dr Mark Sloan was defended by Matlock when Sloan was accused of murder

All My Children and Loving feature the fictional Trans Global Airlines

All My Children and Loving crossed over a number of times.

The City spun off of Loving survivors of the Corinth Serial Killer leave Corinth to an apartment building in NY SoHo