Requesting help with how to use 3D Model Face Alts (Neptunia)

[BluCappo]

Hello! So I'm currently working on an animation, using a model I recieved from Models Resource. I was lucky enough for this model to already come with its own rig, and its been working very well for me so far. I do notice however in the Nep files, there are other faces that can be used. I'd like to try using the faces so my character doesnt have a blank expression on their face. If you know how this is done, please share!