Start with an account, click the small arrow to add sub-accounts.
A new sub-account shows up with the amount of the existing account.
Note that sub-accounts do not carry account numbers.
Edit sub-accounts like every other account.
Add or delete sub-items
Click + to add a new sub-account below.
Click - to delete a sub-account.
Collapse or expand accounts with sub-accounts for overview
The small arrow on the left identifies sub-accounts. Click this arrow or the arrow on the right to expand or collapse the list of sub-accounts.