Originally Posted by UVAhoo06

I tried to do this, but it turns out that the underlying fare class (e.g., X, V, K, etc.) determines whether you can SDC into another flight. So, if I bought a W fare out of the gate and the underlying fare class is X, the fact that X doesn't exist means that I can't SDC onto an earlier (or later) flight. Two people at the DM desk made this clear o me. If the rules have changed, please let us know, OP!