Partial confirmation of activities is a planning method that allows you to confirm a part of an activity's duration or work. This prevents further rescheduling of the activity because the confirmed part is fixed and cannot be changed. The remaining part of the activity can still be rescheduled according to the project progress and resource availability. Reference: https://help.sap.com/viewer/0c9a2f8f9c1b4a2e8b3f7d0c9b6e1d8a/2020.000/en-US/4c5f7a3e6b571014e10000000a174cb4.html

To control whether the delivery date for an external component assigned to a network activity is defined by the earliest or latest scheduled dates, you can use the scheduling parameters for the network. An external component is a material component that is required for executing a network activity and that is procured externally from vendors or other plants

Billing plans are used for revenue planning in customer projects because they allow you to define billing dates and billing amounts for each project phase or milestone. Billing plans can also be used to create billing requests or invoices automatically based on the billing dates and amounts. Billing plans help you to plan and monitor the cash flow and profitability of your customer projects. Reference: https://help.sap.com/viewer/0c9a2f8f9c1b4a2e8b3f7d0c9b6e1d8a/2020.000/en-US/4c5f7a3e6b571014e10000000a174cb4.html