I need help making this character face blink (live2d/facerig help)

I've been trying to make this character blink, by having this blink be shown whenever I open my mouth since I can't do an animation like an audio visualizer I thought this would be a quick fix to have that illusion. I just can't seem to tie the opacity going down and up whenever the template opens and closes his mouth, it just stays on the whole time, can anyone help me please I've been at this for 2 days and I'm at my wits end @n@ here's a picture of what my project looks like, I had this character commissioned and I really hope to finish it someday lol
https://hyper-con.tumblr.com/image/164119273123