OneWorld22---
You are correct in your statement about TWA/AA being less than sweet; far from it actually. In UA's case, the last real merger they had was with Capital Airways in 1960. Over the years, they've acquired various assets and routes, such as PA routes to the far east in '85 and LHR-USA routes in '91, but no real mergers.
As far as AA/TWA, AA has furloughed 42% of TWA's pilots (up to 8 years seniority), and 50% of TWA's F/As (up to 25 years seniority). AA has only furloughed 3% of their own F/As and 4% of their own pilots, an obvious disparity. AA Pilots & F/As with only 1 or 2 years of service stay, while many TWA workers with 9,15,25 years get laid-off. Not exactly 'sweet and kindly' treatment by any means, is it?