Windows has a set way of assigning drive letters.
For the most part a hard drive will take priority over a removable device, or one with removable media inserted in to it.
By adding another hard drive or creating a partition of an original drive C:
The new drive or partition should move the drive letter of the removable media device down it`s letter chain of media devices.
HD C: D: CD drive E: F:
You can use windows disc manager of windows, by typing : Disk Man
Right clicking on a drive or device and change drive letter.
As long as it is not in use by another device in the letter chain. The result of having two drive letters the same will render one unseen by windows, or like it has, disappeared, or is not functioning.
That is...