Need help with rigging. {[Bone Constraint]

I need some expert guidance on this. In my current rig(Image below), I have added a “Child of” Bone Constraint to the “Props” bone(Yellow cube). It is link to “Arm2” bone(red cylinder).

enter image description here

My intention are, if I turned the influence of the bone constraint to 1, the “Props” bone(Yellow cube) will follow the transformation of “Arm2” bone(red cylinder). Like shown in image 2.

enter image description here

However, problem arise when I start to move the “Body” bone(Blue Cube). As shown in the 3rd image even though the influence is 1, “Props” bone(Yellow cube) will not fully follow the “Arm2” bone(red cylinder).

enter image description here

I aware this is cause by both “Props” bone(Yellow cube) and “Arm2” bone(red cylinder) are being parent to “Body” bone(Blue Cube). Hence, when “Body” bone(Blue Cube) rotate both the "child to "constraint and “Body” bone(Blue Cube) are competing with each other in influencing “Props” bone(Yellow cube).

So I’m looking for a way to temporary switch of the parent influence of “Body” bone(Blue Cube), when "child to "constraint is active. something like a switch. However, I am open to other possible option or method.

Note: I need the both “Props” bone(Yellow cube) and “Arm2” bone(red cylinder) to be parent to “Body” bone(Blue Cube) as in most animation I need both of the child bone to follow it. Only in specific situation where I need the “Props” bone(Yellow cube) to follow “Arm2” bone(red cylinder). Like a character picking up an item.

I apologise for not showing the actual model, I bind to confidentiality.

The following is my blender file
Q1.blend1 (916.2 KB)

Hi,

maybe it can be solved this way,
constrain

body and arm2 has a childbone(circle_shadow-bonedisplay)
switch_pose blends between these position(pose_arm2=pos_body) and the child props.001 weights the yellowcube.

Q1_back.blend (1014.8 KB)