I don't have all of the details with me, but if I have my facts straight, Three's a Crowd was for a time, added to Three's Company's syndication (https://radiodiscussions.com/threads/happy-days-again-laverne-shirley-company.567681/post-5053193) package (https://tvtropes.org/pmwiki/pmwiki.php/Main/SyndicationTitle). It was called on screen (https://www.hometheaterforum.com/community/threads/the-ropers-and-threes-a-crowd.368215/post-4893805), Three's Company, Too and instead of "Side by Side", the theme song was an instrumental rendition of "Come and Knock on Our Door".