Dependencies are only for the Discounts&Surcharges Line Item and for Restricted Maximum Demand Line Item.

For Discounts&Surcharges:
Add a Discount Line Item, then in this screen select the Discount Line Item in the Dropdown,
and tick all the Line items that receive discounts.

For Restricted Maximum Demand:
Add 2 Demand Line Items (one with normal MD and the second with the specified TOU calendar)
Tick Enable Restricted MD on the second one.
In this screen select the first Demand Line Item in the Dropdown
and tick the second Demand Line Item as the dependency