Animation Question: Creating new Bones for IK purposes

A while back, I edited the default sim rig just to add a few IK Bones. The was no need to weight paint any differently, though I did edit a few of the bones (mainly the ones in the arms and legs) in edit mode to make them visible/attachable to one another, which made adding IK bones much easier. The model works beautifully in Blender, but much to my chagrin, it does not translate well into the sims 4 studio. I was wondering if there was any way to remedy this. (I want to be able to edit the sim object to match my rig, but there's no way to position the head and tail of each bone separately. I'm not sure if I'm missing something important.)

Any help is appreciated. Thank you.