Use this API to add a family member under a retail primary client.

This API supports two onboarding paths:

• create a new linked customer for the family member
• link an existing active person customer by linkCustomerId

To create a new linked customer for the family member, isCreateCustomer must be true. If isCreateCustomer is false, no new customer is created.

When linkCustomerId is provided:

• the existing linked customer must be an active PERSON
• the existing linked customer cannot already be linked as a family member
• the existing linked customer cannot already belong to another primary client

Linked customer lifecycle:

• under 18: a newly created linked customer is activated automatically
• 18 and above: a newly created linked customer remains pending until standard retail verification is completed