I love the idea of trading up! Would you explain it a bit Further? I have a horrible resource guarding old dog right now.
I think if you already have a guarder you need to be very careful. It's going to be a slow, trust building thing, which can take some time. As I said, once I give my dogs something, it's theirs. They can voluntarily give it back (in a game, for example), but I'm not going to take it by force. Many people think that taking things away from their dogs routinely and then giving them back will help the dog learn that it's okay, and sometimes, with some dogs that works just fine. But the potential for blowback with that method is huge because it can actually trigger the opposite response, where the dog doesn't trust that at any time you may just randomly snatch away something it values!
As I mentioned, I also do impulse control stuff from the beginning. Even a young puppy can hold a sit for a fraction of a second while you put down the food bowl on the floor, and then release it to eat. I started that when my dogs were young puppies, very easy at first and then gradually more challenging. In this photo my husband has put Halo's dinner on the floor and she's sitting and watching him, waiting for the "okay" to eat it:
In the early stages, the puppy is further from me and the bowl, so I can quickly stand back up if puppy breaks the sit and tries to get the food. Once puppy sits, I start to lower the bowl again. I do this as many times as necessary, until the puppy realizes that the way to get meals is to wait until the bowl is on the floor and I release them. Eventually, I can be several feet away with the bowl right next to the pup, and they will not eat until I say so. I own the food until I say it's the dog's.
I spent time with her every day doing this impulse control game by Susan Garrett, a well known agility trainer and competitor:
It's basically a default "leave it" since you never actually tell the dog anything, it learns that the way to get the food is to ignore the food. I add eye contact, the dog has to look at me. These eventually become very strong default behaviors, where my dogs routinely sit and look at me, awaiting permission to proceed, without me having to nag them about it. I own what's in my hand until I say it's the dog's.
Same thing with trading games. If you play with tug toys, you maintain possession of the toy by continuing to hold onto it. Have the dog "out" the toy (I start training this by putting a small piece of yummy, smelly food right at the dog's nose), when the dog drops the tug to each the treat, I mark it ("yes!"), and then we play tug some more. I do this with bones too, and balls, and any other of the dog's toys. Gotta go for now, I can expand more later.