Add Properties without change exisitng class- OOD Design

http://www.1point3acres.com/bbs/forum.php?mod=viewthread&tid=138800&extra=page%3D1%26filter%3Dtypeid%26typeid%3D200%26typeid%3D200
Design a class which stores demographic information of a person like name, address, phone number, male/female. 
What if the person has any prefix to the name, multiple phone numbers/addresses, 
how will you handle dob in case of multiple locations
(If a person is both at 12 PM in USA on a date, then that date is different from date in India), 
how will you handle the validations of these fields when the user enters the values


目前的想法比较单纯 Code 大概是这样

class Patient {
        String name;
        String address;
        String phoneNumber;
        boolean gender;
        String dob; 
}

但是要加 prefix 或 multiple phonenumbers/addresses，就要去改变的类里面的变量。
应该能有更好的方法吧 ..

public interface Factory{
public Patient getPatient();
}
public interface Patient{
public String getName();
}
public class PatientBean implements Patient{
String name;
@Override
public String getName(){
return this.name;
}
}
public class BeanFactory implements Factory{
@Override
public Patient getPatient(){
return new PatientBean();
}
}
public class Test{
public static void main(String[] args){
Factory f = new BeanFactory();
Patient p = f.getPatient();
System.out.println(p.getName());
}
/*After couple of month, add a prefix before name*/
public class PatientBeanV2 extends PatientBean{
String prefix;
@Override
public String getName(){
return prefix+" " + name;
} 
}
//modify class BeanFactory, getPatient() method, return new PatientBeanV2();

想请问这样子如果没有prefix 但有两只phoneNumber 就需要再新创一个类(PatientBeanV3) 吗？

如果这个需求是第三次提出的话那么我认为答案应该是yes。如果不可以直接修改原来的code的话