In Reply to: Oz - Bali/Singapore/KL with other's kids posted by MrsWelch on Thursday, 19. February 2009 at 19:45 Bali Time:
My children flew to bali with my cousin and brother last year. I typed up a letter saying that they had permission to travel with them and I also gave consent for any medical treatment that may be needed. I put my address, contact number, passport number etc on the letter.
If you google "letter of consent to travel with minor" (or similar) you will find plenty of samples.
My brother or cousin were not asked to produce any form of consent either here or in Bali, but my brother did say that in Perth they told the girl when they were checking in that they had a letter.