Well I don't know them off the top of my head but listening to Pav on Nova this morning he mentioned that back in 2001 (he had a bad season and missed that parents) he had a word with Schwab saying that he was aware he is still in contract but should Freo want to do some sort of swap with any of the SA teams he would be happy enough being traded back. I was shocked and sad to hear that but, hey, water under the bridge and remember he was only little at the time.
Now in the case of a club flat out trading players. I believe this is what happened with Broughton. He didn't want to go but Freo wanted to trade and put Broughton on the table. I don't think players have a choice as to whether they get traded or not. Which totally sounds dodgy.
In summary I probably didn't help you out at all but this is one of the reasons I don't really follow all this trading shlemockle. I have no idea what's going on.