QS8 MIDI out to Scope MIDI in, Scope MIDI out to QS8 MIDI in, QS8 MIDI thru to Terratec MIDI in.
Inside Scope you will Route The Scope MIDI Source (signal from QS8) to the Sequencer MIDI dest, or the internal synths or whatever you need to reach from the keyboard . At this point, If you use a Sequencer, you'll connect Sequencer MIDI source (signal from daw) both to Scope devices (synths, mixers for automation etc.) and to Scope MIDI destination (card's MIDI output).
From Scope's MIDI output you go to QS8 MIDI in, so you will receive the messages coming from the sequencer to play QS8 sounds, then you'll connect QS8 MIDI Thru to Terratec's MIDI in, to have Terratec receive signals from Scope.
Naturally you can tweak the MIDI routings in Scope or use it's MIDI merger modules, when you use the daw put the QS8 keyboard in Local off mode (I don't know QS8 but it should be easy).
This if you want to have everything connected without buying any further devices.
In fact Scope has got an infinitely flexible routing both for Audio and MIDI, it has MIDI merger modules and there is also a MIDI multiple switch as a freeware somewhere on PlanetZ.
BTW Scope has MIDI thru too.
