afair you can create/destroy anchors when fingers and the object intersects. you can test that with raycasting. to make it natural you have to take grabbing, velocity of contact and opening fingers into account.
simple way is taking the object out (destroying) of the simulation right when you grab it and display an imposter while holding it. you can inputmorph the last known simulated position to the imposter position to make it look convincing.
and when you release the object, just create a new bullet object at the position of the imposter. its just a matter of good timing to make this convincing.