What is the purpose of 'New Start Date' field when employee edit any Family and Emergency contact?

Summary: What is the purpose of 'New Start Date' field when employee edit any Family and Emergency contact?

Content (please ensure you mask any confidential information): When an employee navigates to Family and Emergency Contacts > Click on any contact > Click on edit icon under Relationship section, there is a field labeled as New Start Date which is a required field. What is the purpose of this field?

As we already have a When does this relationship change start? required field which captures the start date for change in the relationship.

Version (include the version you are using, if applicable): 24B