https://sims4studio.com/thread/11/tutorial-check-accessory-assignments-blender

When you first get the EA accessory into Blender you can check its bone assignment by using the following steps:

1. Go into Edit Mode.

2. Change the shading on the model to solid.

3. Click the n button on your keyboard to bring up a menus bar on the right side of the viewport window. Scroll down until you see the Mesh Display menu and click Show Weights.

4. Click the Object Data button - it looks like a little upside down triangle.

5. In the Vertex Groups section you will find a list of the joints present in the mesh.

6. Click on the joints one by one until you find the one that makes the accessory turn bright red. This is the joint that the accessory is assigned to and the one that you will need to assign your new accessory to.

7. You can check the assignment on your own item using the same steps to check that your bone assignment is correct before you save it.

If you have any questions about the tutorial please post them here