How to create sub galleries
Sub galleries are made up of a parent gallery and then unlimited child galleries. Each child gallery is a separate gallery assigned to the parent. This allows you to make unlimited hierarchical depths of organization for your galleries.
Create a gallery
Create a gallery like you normally would
Setup hierarchy
When adding/editing a gallery, find the "Parent" option and click to show the window where you can then select which gallery you wish to be the parent.

Still need help?
If you have not yet found your answer in the documentation articles, please contact support