How to apply for a HKID card for a Canadian born 18-year-old whose parents hold HKID cards?

The 18-year-old will visit HK from May to July, 2012. Her parents will also go to HK from mid to end of July. Her parents were born and they grew up in HK but migrated to Canada about 20 years ago. Is the daughter eligible to obtain an HKID card? What is the fastest and easiest procedure? What kinds of document are required? Can she apply for the HKID herself with sufficient supporting documents, or her parents need to be present when the application is submitted? Can the application be submitted online? Can an appointment with the government office be scheduled online before she/they arrive HK? Please provide as much relevant information as you can. Thank you.