澳大利亚过境签证876表格

一家三口（小孩3岁）经澳大利亚过境去新西兰，
1. 三个人必须分开填写876表格吗？
2. 如果是，那么表格中details of other persons included in this application and in your passport需要填写吗？
3. 3岁的小孩如果分开填写的话，那么occupation，employer's name和employer's address处需要特别备注是学龄前儿童吗？
4. 我和我先生去过澳洲，小朋友没有去过，那么如果分开填写且问题2不填写的话，小孩那份里面have you or anyone included in this application ever previously applied for a visa or travelled to Australia打NO还是YES？