Then Brisbane start talking to Port Adelaide about a possible deal.
You attempt to do a deal with Port Adelaide, because the preferred designation is Port. If that breaks down, you sound out Aish whether he is prepared to move to Adelaide. If not, you go back to Port. If so, you deal with Adelaide who may offer less because Port are now out of the picture. Hypothetically.
I think you are missing the point.
The process you are describing is the one I would expect were a player to simply say I need a move, and here is where I want to go, suck it up.
Except, we keep being told this is entirely about his dad, and we must all be extremely considerate and of course holding him to his contract which he signed in good faith would be morally wrong. So I keep wondering at what point in the above, if he refuses to countenance Adelaide in the hypothetical (or GC in real life), you ask, candidly, if this is really all about his sick relative or he just wants out to Port, always wanted out to Port, and we can stop pretending we have to do this deal if we dont want to be considered to be terrible citizens and admit this is a bank heist without balaclavas.