as I understand it you want 3 copies of the songs in 3 different keys.

1) the permanent way:

you must copy the song twice in the sequencer so that you have 3 songs.

then either step edit the control track of songs 2 and 3 to point to the panel bank 2 and 3 where the transposed setups are memorised, remembering to panel write the correct starting conditions for each one...

or even easier, disable transpose in the panel memory expand mode filter, and use the panel write to set the starting key for each song.

2) the easy way:

disable transpose in panel memory filter and save the current panel with the other files.

you can use just the one song and one panel memory bank, as long as you set the transpose manually after you have done the sequencer reset, and before you start the song.