cryptsetup-multidisk-ssh/readme.md

This is the standard archlinux encrypt hook extended to support multiple encrypted devices via cryptsetup= cryptsetup1= cryptsetup2= etc.

Hopefully one day it will be merged with the normal archlinux cryptsetup package (ask for it here), until then it will be available via the aur here:

https://aur.archlinux.org/packages/cryptsetup-multidisk/