How do I rig a double-jointed knee with IK properly? want to export rig to PMX format

[wikid24]

Hi I have an issue with a double-jointed knee I want to export to PMX format:

Standard PMX rig looks like this (from uuunaya asset import, Genshin Impact model):

However my rig is a double-jointed knee (top of knee is ankle_L, bottom of knee is j_asi_c_l), so the control and IK is all messed up using the standard IK rig for Ankle_L. How do I rig this properly so that when I export this to PMX format there are no issues? Essentially I want j_asi_c_l to move with ankle_L as well as put in the proper IK constraints so that it respects the ankle_L movement. What I am not looking to do is merge the bones ankle_L and j_asi_c_l, because then I have to deal with a host of issues re: weight paint transfer and I want to retain the original bones as much as possible when exporting to PMX format).

Here is a screenshot of it, bones are out of alignment because of the IK rig structure not working with the double-jointed knee.

Any assistance would be appreciated!

[wikid24]

here is standard genshin rig:

https://user-images.githubusercontent.com/19479648/214689805-80a1f428-bd3f-4fc3-8a1f-7b78ae0a6d29.mp4

here is my double-jointed knee rig (using the same IK setup):

https://user-images.githubusercontent.com/19479648/214689916-0d6eb46f-fbb7-41db-a22e-5c0d81dd6586.mp4

[wikid24]

here is a sample blender file of my rig nala_IK_work_copying_mmd_rig_style.zip