Actually, this is not a FF issue, its a "hold" issue. When teaching the hold command, you can simutaneously teach a nice delievery to hand. When the dog is holding, tap the dumbell, roller, etc. If it is dropped, ear pinch and reinsert. repeat hold, and try again. Only when you say "Drop" or "give" or whatever else you want to say, does the dog get to release the object. usually in your hand.

Once again, FF is a way of FORCEING a dog to retrieve no matter what, he has no choice, you are in complete control of the dog, imposeing your will, the dog must comply or he will get some discomfort until he complies. This is what makes a dog never give up on a retrieve, never refuse, or he gets pressure (e-collar, ear-pinch). When FF is done right, it is not going to hurt your dog, the whole point is to show them that you are in control, they can do what you want and "turn off" the pressure, or they can sit there like a piece of lard and recieve discomfort, but not pain.