Thanks for the post, although this may be more of a DAW question than an interface question, we'll await more details on the OP's setup.
That said, if you haven't yet discovered the Routing Presets in Mix Control, please take a look at the 'Mixing' Preset. This will route each output on the interface with the corresponding DAW output. For example, within your DAW, if you send a particular channel to output 4, this will send just that channel out over output 4 from the Saffire.
Hope this helps
Let us know how you get on.
Simon // Focusrite Technical Support