Hand IK towards Bow string notch (with blendspace bow draw distance)

Development Character & Animation
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Context

I want my characters hand to always rest on the notch on a Bow string, during the animation where the bow is pulled back.

The Bow skeleton’s draw animation is a BlendSpace based on how far the string has been pulled back.

Here is the animation without any IK

Here is the animation with two bone IK applied

And here is the animation with two bone IK applied, but also being driven by the distance that the string is being pulled back

As you can see, the hand jumps all over the place, probably because

  1. The IK changes the position of the hand
  2. which changes the bow draw distance
  3. which changes the target position of the hand
  4. Repeat step 1

Project Setup

I have a Bow with an Animation Blueprint which sets the amount the bow is drawn based on the distance between the left and right hands (minus the distance from the idle string and the handle), when the right hand is holding the bow notch (via anim notifies) and uses a BlendSpace to blend between not drawn and fully drawn

Bow firing blueprint
Bow firing blueprint1016×504 96 KB

I also have 2 bone IK set up which moves my hand bone to the location of my Bow string notch (which is accessed through a separate skeletal mesh reference that I have stored on my Character)

image
image2048×1092 290 KB

The character animation is a different animation to the one for the Bow’s draw distance (different assets, different animators)

Problem

GIVEN the Character is playing the animation to draw the bow
AND the bow is setting the draw amount of the string as a result
WHEN the Character applies Hand IK
THEN the Bow draw distance doesn’t increase

I believe this is because the hand is being moved toward the notch because of IK, which then sets the new draw distance to 0 and prevents the BlendSpace from being updated.

Instead, I need the following outcome

GIVEN the Character is playing the animation to draw the bow
AND the bow is setting the draw amount of the string as a result
WHEN the Character applies Hand IK
THEN the Bow draw distance is applied and the hand is moved to the new notch location

Question

I believe the hand is already the correct distance from the notch, since my bow is taking care of that by setting the draw distance.

How can I change the other positions of the hand to match up, whilst not moving it toward the notch?