Keep character talking but with 'worried' mouth folder lipsync replacing default

EDIT: Whoops, I found the answer in this thread! How do I use a variety of mouth sets while computing lip sync from scene audio? 

I have a talking character who I want a default neutral state for, and also a worried state. I'm starting off with a 2 frame eyebrow change and a different mouth set.

My eyebrow replacement worked great - 'w' triggers a concerned eyebrow animation which replaces the default eyebrow.

I thought I could do the same with a mouth replacement so I made 2 subfolders within the +Mouth folder - 'Normal' and 'Worried', which has subtly different mouth shapes.

When I trigger the worried state with the 'w' key, I see the new worried neutral mouth but the lip syncing animation stops and he's just mute!

How can I have him continue talking with a worried face, but using the new folder of mouth shapes for lip sync? (I don't want to replace the entire head folder with a worried version although I know that works too.)