Sculpting Shape Keys with Multires Modifier?


I’m modeling a character and doing expression tests with shape keys. She has a multires modifier and the sculpt mode changes I make to shape keys doesn’t seem to apply (or rather it messes up my base mesh). I looked up the topic and apparently multires is incompatible with shape keys, but this tutorial I’m following seems to do it just fine? (link should jump to the timecode)

They also do some combo of multires and shrinkwrap earlier in the video, but their explanation is so fast I can’t follow it. I don’t know what they mean by “apply sculpt to base mesh instead multires layers”. Does this have anything to do with my problem? (again, this link jumps to the timecode)

Can someone shed some light on this? I’m still a beginner. Is there a way to use shape keys without applying the multires and losing the low poly mesh? Would a subdivision modifier be compatible? The subdivision modifier seems to make the toes and fingers really thin unless I make the geometry in the base mesh overlap.

Here is my model


From what i understand they simply sculpt at the base mesh. And not at one of the layers. Which makes sense, since when you apply the multires modifier then the low poly mesh and its shape keys is lost. You create a new geometry by that.

But i haven’t toyed around a lot with these things yet.