Trouble is, that link (nor any of the other threads) deal with what I know my questions (and I believe a core focus of the original poster) is.

Specifically:

If you did the BUMP with an AA ticket on your outbound leg, what happens to the return?

The linked thread makes a mention of "call the original carrier (in the example, AA) and make sure they don't cancel the return portion." But is that a specific obligation? Does the 'original' carrier have to keep the return leg open for you?

All the threads in the search at best mention what appear to be return portions of trips -- there's no specific mention of having/not having issues with return portions -- something that could really bite, having to purchase a walk-up fare because your return portion was cancelled.

In other words "Gee, we're sorry, sir, but the computer automatically cancelled out the return portion when it saw the outbound left and you werren't on it, and there's nothing we can do to override it."

That information is what would be appreciated.

Steve