SS Change Checkout Contact Detail Process
The workflow for changing the contact details during checkout is shown in the following image.

When the SS Change Checkout Contact Detail workflow is called, the following happens:
The process updates the selected contact on the quote and sets the contact name in the Recipient Name field.
Based on the selected contact name, the process updates the shipping and payment records.
The process calls SS Set Shipping Checkout Mode Process (see SS Set Shipping Checkout Mode Process) to set the mode for the checkout view and then reprices the quote based on the selected contact name.