Here's a link that tells you how Ross and West teamed up in the 1940's...

Read the entry on "Ross Martin '41". And yes, it's bizarrely convoluted. The connection to Three's Company is around the middle of the story.

http://newman.baruch.cuny.edu/digital/2001/history/exhibit/chap_09/who_made_big/made_big.htm#martin

Except for a quick reference in Mann's book to RW's vaudeville past, I'd never seen any of this before.