Question Constraining object position with source object parent movement

I know that it's common to parent the IK targets of arms to the weapon/object you're trying to hold so that way you can just move the object and the arms will follow. However, in my situation, I want to be able to control when the right hand IK target's position becomes constrained, so I tried using the multi-position constraint. I was able to constrain the right hand IK target's position to a child object of the weapon I'm animating, which worked how I thought it would work initially. Wherever I moved that new child object, the IK target would follow. However, when I moved the weapon, the IK target did not follow. I'm assuming this is because it's local position wasn't actually changed, and animation rigging constraints only update on local transform changes. So my question is, is there any way to constrain an object's position to a source object's position even if that source object's position was changed by it's parent?