Why does nobody ever try to simply change the field skeleton and animations?
It is a far easier approach, and once you do it, you can just back up the field animations and never need to do it again, for any project as long as you inject the proper animations and be done with it in a matter of moments.
To do it this way, you simply need to do a hard swap of the physical field animations of Nanaki with another skeleton, such as Cloud, Tifa, Barret, etc.(for this purpose, Barret is best.)
Then you'd open up a different field skeleton with a hex editor and change all the parts in it to something else easy to do, such as for barret's field skeleton to be instead of axxx, to nxxx and then rename all the parts, and this will work ingame.