First of all thanks for that info, useful stuff to know and I didn't realise you could link a MIDI track to an audio track with a synth mounted in FX like that.
But back to my issue. If I link a VST that outputs sound using this method all is well, but this ChordMem VST doesn't output sound. What it does is let you program a series of notes to a particular key press to enable you to play complex chords with one finger. As an example, if you press a middle C it will send out midi information to sound several notes, whatever the middle C key has been programmed with. So to operate it needs an input from a MIDI keyboard and output to a soft synth, but I can't see how you can insert this VST in the middle of a chain such as MIDI keyboard > ChordMem VST > VST synth.