partition without drive letter assigned

How does Defraggler identify disk partitions? I have multiple disk partitions on my laptop and Defraggler displays only those disk partitions which have drive letter assigned (and only these can defrag).

E.g. there are three disk partitions. The first is assigned drive letter c:, the second is assigned path c:\home and the third is assigned path c:\home\hidden - is there any possibility to defrag second and third partition by Defraggler without having to assign drive letters to these partitions?