The devoted mother of Bhutan-born conjoined twins has confidence that Melbourne surgeons will be able to separate her beloved daughters.

Devoted mum Bjumchu Zangmo is confident Australian surgeons will separate her conjoined twin daughters who are scheduled for surgery a long way from their Himalayan home.

Fourteen-month-old Nima and Dawa are joined at the torso, but surgeons at Melbourne's Royal Children's Hospital plan to give the girls their independence during a marathon procedure on Friday.

"The doctors here in Australia are one of the best in the world and I have all the confidence that the operation will be successful," Ms Zangmo said through a translator on Tuesday.

The Bhutanese twins are coping well since arriving in Melbourne last week.

"They are very happy, they are jolly and after coming to Australia they are more exposed and more happy," she said.

Ms Zangmo also expressed her gratitude to the Australian public for the support she's received.

"It's beyond words to express my gratitude," she said.

After extensive tests and scans the surgical team is confident about the operation, which will include splitting the girls' shared liver.

"We feel we are in a position to give mum her ultimate wish which is to go forward with the separation of the children," pediatric head surgeon Joe Crameri told reporters.

"We've been able to review some sophisticated scans that have been done ... in simple terms the plumbing certainly looks favourable to us," Mr Crameri said.

"Certainly we feel it gives us the opportunity to separate the twins and to preserve good function for both girls."

The girls share a liver and they are believed to share part of a bowel but the extent of their combined functions will not be known until the surgery is underway.

"The imaging seems to be favourable in terms of what we need to achieve but surgery is always a case of 'expect the unexpected' and certainly that will be the case here," surgeon Tom Clarnette said.

The liver specialist added the procedure could take six to 12 hours and posed a risk.

"Getting the separation is going to involve getting the liver divided safely and there's a blood-loss potential there," Mr Clarnette said.

The surgery and recovery are estimated to cost at least $350,000.

The state government pledged to cover surgical costs, with other funds raised to go towards the girls' Australian rehabilitation and return to Bhutan.