Holmes, who is believed to be in her eighth month of pregnancy, is set to join Cruise on the 14-hour flight from Los Angeles to Sydney, despite doctors' advising flying close to term can cause complications.
Cruise is attending the Sydney Opera House memorial to support his friend and Kerry's son James Packer. The MINORITY REPORT star convinced James to undergo a Scientology self-improvement course in 2001.
Meanwhile, Oscar winner Russell Crowe is set to deliver a eulogy at the service.
Billionaire Kerry, the 94th richest man in the world, died in December (05) at the age 68.