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!

[Qw2]

What software are you using to animate? I'm aware of how it should work in MMD and Blender
For MMD, you need to create a UV morph that will allow you to offset the texture coordinates. I often don't bother trying to do this in pmx-editor and instead use Blender + mmd tools. It's a bit complicated so if you'd like I can make a video of me doing it, but then once the morph is completed you can just use the slider to change it.
For Blender (2.8+), you want to use the Shader Editor and then use mix nodes to swap between UV Maps for each face. What I like to do is use a driver to animate it, but you can also just animate the mix node itself. As you can tell from this explanation this is also kind of complex so I can demo this also.