Blendshapes and Wrinkle Map workflow
polycounter lvl 5
Hi
For a character I'm planning on making, I want to make use of Wrinkle Maps. I found out recently on how to get them setup in Unreal thanks to this link - https://www.artstation.com/blogs/leahmcewen/0Yl7/dynamic-wrinkle-maps-in-ue4. Then, after coming across this thread on CGTalk/Society, they've outlined a workflow for making them - https://forums.cgsociety.org/t/how-to-create-proper-wrinkle-maps/1848108.
As I'm still new to all of this, I want to double check with others on approaching them. That thread suggests to do the rigging/posing first and the export into ZBrush and sculpt in all the wrinkles etc. Making use of the Layers. Then you can use a plugin in ZBrush to export them as Blendshapes into Maya. Would it be best though to sculpt in my facial expression once the high poly is done...? I only plan on making a simple scowl or something. I imagine, that if I took the low poly after it's rigged, and then add the new expressions, it would be too low to work with. Would I then need to make two separate bakes for the Normals, along with a mask for each one for when I set them up in Unreal...? Please someone let me know if I'm missing anything else, or if there are other considerations I need to make. 
Thanks.
Thanks.