Hi Diki.
Very sorry but I'm not sure what you mean. No KORG Keyboard can assign a song to a COMBI.

Midi files do not hold any advanced information like Tone Adjust settings, IFX information, key zones, transpose values, and so on. It's a crude and slow format that even depends on the first measure of the song to contain the Control Change data for the song to simply function.

KORG's SNG format on the other hand stores everything there is that relates performance of that song and every feature of the Sequencer and the effects engine.

In addition to that it is a true instant start format. The split second you press that button the song is playing with everything already assigned.

Load one song file, and you could have about 30 songs (which is aprox 210,000 notes)instantly available in memory.

Regards.
James.