I have done that but i think it was just by unchecking 'remove conflicts'. Gets you control over 2 parameters with 1 knob. The automations will 'take over' once you let go of the knob if I remember correctly, can lead to some weird effects.
Ok worked it out. You just need to create a "New Link" for each source. So, for example, say you have your automation already assigned to adjust filter cut off, it will be listed under Internal Controller - Automation Clips. Now you need to click on New Link, then just move the knob on your control surface. It should pick it up, now you will have 2 links for the Filter cut off.
Spent WAAAAY too long trying to work out something so simple.
WTF I never do it like that. If I create automation of say, synth filter cutoff, for the intro of a tune for example, it doesn't prevent me from linking the same parameter to a knob on a controller, and the automation will work despite the midi link. I don't understand.
I dont understand either then. But thats the only way I've managed to do it. Logically it makes sense, as surely you would need 2 sources to control the same knob by some kind of identifier. In the window what does it say its assigned too??? It must be listed as automation clip or MIDI controller....but can't be both on the same link surely