You can change the parenting of a prop BUT you need to be very careful.the parenting of the object is a global (same in all frames) so IF you need to change anything in a section already done you need to remember to reparent the prop while making the changes. If at frame 1 you parent a prop to a figure and record your keyframes to (for example frame 90) the motions of the prop will be recorded in the keyframes to that point. If you then change the parenting of the object and record keyframes from frame 91 to end of animation all of the object movements are stored with the new parenting in effect. The other method of using two objects is preferred if you need to be adjusting the two sections of the animation. An alternative to scaling the object to make it invisible would be to animate the texture.