Question Bones missing after importing animation into unity.

Hello People of the Unity Forum.
So i've got a problem with importing Animations from Blender into Unity.
As you can see the bones of the base model of my character are just fine in the hierarchy and everythings green (dont mind the sword).



But when we look at the bones of the animation, we will see that the lower legs and the foot bones are missing. I found out that its because inverse kinematics were used on these bones in blender and they are therefore not correctly in the hierarchy.







I told my friend that he should just parent them normally again, but he said that would just ruin the whole animation, as inverse kinematics dont work when theyre parented.

The animation not having the same rig as the base model is destroying the whole animation and its just looking very weird. My question is now, how can i or my friend make the rigs of these two models be the same, without touching the ik or destroying the animation in any way? Because i tried to parent the foot and the heel normally like its in the base model, but then it just looks weird. Also, i want the animation to be humanoid, because then i could just use the same rig that i used on the base model, but thats just not possible when the foots missing, i just get an error.

Any help would be appreciated. I am sitting on this problem for like a week now and i havent found any solution that could help me.

Thank you in advance.