After the phenomenal success of Three's Company, it was a foregone conclusion that there would be a spinoff. Enter Vicky Bradford (Mary Cadorette), flight attendant and Jack's love interest. The premise for Three's a Crowd was set up in the last three episodes of Three's Company - Jack meets and falls in love with Vicky, but she doesn't want to get married, due to a general distrust of the institution. They decide to live together instead, much to the consternation of Vicky's father (Robert Mandan) who becomes the landlord for their apartment and for Jack's new restaurant downstairs.
Three's a Crowd was not a big success - it only ran for one season. Also featured in the series was Jessica Walter as Vicky's mother. The show occasionally airs on the Antenna TV cable network, though it has never been released on DVD. The first half of an episode titled Family Affair is above, uploaded to YouTube by canw1, though the second half is not available.
Obscurity factor: 9 (not on DVD, not well remembered, partially available on YouTube)