Lock single partition for WD My Passport Ultra

It would be great if you guys added the ability to lock partitions as i use my drive to boot Windows 8.1 portable from a 100gb c:\ drive partition and store my files on the remaining 1.72TB partition.

I only want to secure the 1.72TB partition but WD Lock insists on locking the entire drive thus stopping the portable copy of Windows 8.1 from being able to boot.