You can add new work contract records to an employee using the <PreSaveProcessType="ManageWorkContractsProcess" /> tag.
When you add this tag to an XML form, users can assign new work contracts on the form by selecting a new start date. When they submit the form, the application creates a new work contract record using the date provided on the form as the start date. It also end dates the existing record using the date of the day prior to the effective start for the new record.
For more information about work contracts and work patterns, see the Dayforce Implementation Guide.