ok. that means as for the following:
1 ) my drumtrigger is running on MIDI CH2, e.g. transmits a NOTE C2
2 ) -> going to the THRU-port of my keyboard (keyboard running on MIDI CH1)
3 ) -> keyboard plays NOTE D3
4 ) -> the OUT-port of my keyboard transmits CH2, NOTE C2 (from drumtrigger) + CH1, NOTE D3 (from keyboard)
5 ) -> all this is passed into my "converter-box"
6 ) -> converter-box reassembles the midi message as a mix of drumtrigger and keyboard.
7 ) -> sends the new note-value (from keyboard) with the note-on from the drum-trigger
8 ) -> this new message is received by the synth (last in line) on MIDI CH2
(is this understanding correct? --> http://img703.imageshack.us/img703/1595/4dqx.jpg
the crucial point is, that i don't want the synth to react to the stroke of the keyboard, only to the stroke of the drum, obviously using the note-value of the keyboard.