Hi Strawberry. I been down this road too. So i'll tell you what i know.
I'm a BBC (british born chinese) My parents are like yours, born and rise in Hong Kong, i'm not sure what other factor are required... but you must be 18 years old or over to apply. With the laws as they stand, you must return to HK with your parents to apply for your ID Card, they must bring every form of ID with them... especially their HK paper work including Marriage Certificates (don't forget to bring yours too!) - if there is anything missing or wrong, the gov. won't process the paper work and you won't be notified.
But... here's the bad news. If you lose your parents at any time between now and before you apply, You may well definitely lose any right to abode in HK. My advice... come to HK for a family Holiday.
I'm not sure what's happening now with the hand over in 1997, i believe if your granted a Hong Kong ID, you still have to return at least once every 3 years to keep your ROA active. Residents who's ID Cards issued Prior to 1997 needn't return.
So in this case, your friends, i think are correct.
more info: http://www.esd.gov.hk