How to attach gun to animated arms with animation rigging package?

I have a humanoid rig with a pistol idle animation. I tried using the animation rigging package to attach the arms to the pistol but the pistol is stuck in the same position relative to the player. The idle animation moves the shoulders and elbows but not the hands. How do I get the gun to move and rotate along with the idle animation I have WHILE still controlling the hand attach points? I would rather not attach the gun object directly to the hand bone.