Additional disk device (/dev/sdb) on Multipass instance

How do I add an additional disk device on Multipass instance?
Multipass already comes with /dev/sda1 which has its own partitions.
What I am looking is to create another device disk like /dev/sdb and /dev/sdc.

The request is to add devices such as /dev/sdb and /dev/sdc alongside /dev/sda1 in a Multipass instance. Start by reviewing closed pull request #4370 and the existing instance/device handling; the issue names no source file or test. Done should be defined as a supported way to create the requested additional devices, with validation of the resulting device layout.

Written by the indexing model from the issue text.