In my Sicilian for Black (same as in Shpongled's free download), a key position has 7 sensible moves for White. One of them leads to a labyrinth of complexity (8.Bb3)
I want to train on the 7 "sideline" White 8th moves only, to keep things manageable for myself. I don't see how I can cleanly do this with sub-variations. I can do it by creating a nonsense "best" Black reply to 8.Bb3 and marking the real Black response as not best, effectively trivializing 8.Bb3 in training, so this issue is not a show stopper.
I'm just logging this for the future in case some day you decide its meaningful enough. For example, since the (My) Best Moves column is not used for the opponent's move, you may convert it to have a Don't Play This For Him meaning.
Thanks.