Help: Mesh Edit

Hello everyone, how are you? I'm starting to edit/create content for the sims 4. I recently edited two meshes but had different problems with them.

1-The first I tried to edit the mesh of Hondo's clothes, I wanted to make only the head appear, and then add a skin to it. I edited it with blender following a tutorial here, and in sims4studio it works perfectly but when I open the game the error in the photo below occurs.


imgbox.com/YAXhbPvU

imgbox.com/pxZPhXdC

2- I also tried to edit a top (Shirt and Jacket) and turn it into an accessory (Jacket) everything worked, then I edited the texture (Difuse) erasing the part of the shirt, but the error of the two photos below occurs, if I erase the texture the shirt erases part of the texture of the jacket, and if I leave the texture it covers the sims chest. Any idea how I can fix these errors? Something I forgot? Consider that I'm a beginner, and that English is not my native language, so sorry for any mistakes. Any help is appreciated, please help me. PS: I don't know if this is the right place to ask for help, I hope so, but if not, I'm sorry.

imgbox.com/8ZB3VjHS

imgbox.com/uQfoHrqj