You will need the Full Write Groups permission to perform this task.
Setting the hierarchy of a group
Once you have selected the appropriate group via “Groups” in the left-hand menu, open the group and go to "Edit group" from the top right “Actions” dropdown. When adding a group, there is a tab named "Hierarchy" where you can indicate a parent group as well as one or more child groups (a.k.a. subgroups).
Note: By setting a parent group you automatically make the current group a subgroup.
After you have set the parent group, you can also add subgroups from this "Hierarchy" tab for your group.
Note: Group Admins of parent groups can access to all subgroup information
Editing the hierarchy of a group
Once you have selected the appropriate group via “Groups” in the left-hand menu, open the group and go to "Edit" group from the top right “Actions” dropdown. When editing a group, there is a tab named "Hierarchy" where you can indicate a parent group as well as one or more child groups (a.k.a. subgroups).
Open the group, and select "Edit group" from the top right "Actions" dropdown. Then select the "Hierarchy" tab.
After you have selected the "Hierarchy" tab, you can set the parent group by trying in the name of the group next to the parent section.
Note: By setting a parent group you automatically make the current group a subgroup.
After you have set the parent group. you can also add subgroups from this "Hierarchy" tab for your group.
Note: Group Admins of parent groups can access all subgroup information