is it possible to issue a command that causes an 'insert next' or 'append' function

Heh. I almost answered that question in an above post, but decided not to because you had not yet asked about it explicitly.

The answer is no, not at the current time. The reason is that the 2.0 beta 11 software does not have a serial-port command for that purpose. Note, by looking at the code, that Hijack gets away with some of its tricks by injecting serial commands. Since there's no serial command to insert or append a specific FID, it can't do it.

Good news is, that feature will be coming in a future release of the player software. Hope I'm not giving anything away by revealing this, I don't remember if it was revealed before or not.