Millions of people have followed their risky journey to be separated.
But now, just seven months after the life-threatening operation, two-year-old twins Erika and Eva Sandoval are flourishing.
One day, they will probably never remember they were conjoined.
'The whole conjoined thing is like a distant memory,' their mother Aida told the Sacramento Bee. 'I know they were at one time, but this is just our life now.'
The girls underwent surgery on December 6 in Palo Alto, California, to untangle their digestive system, a uterus, a liver, a bladder, a pelvis, and a third leg.
Before, Erika was almost half the size of Eva, as doctors feared Eva was absorbing most of their nutrients. Now, Eva weights 20lbs while Erika weighs 19lbs 8oz.
New life: Erika (left) and Eva Sandoval are flourishing, moving around, and enjoying their new life after being separated in a highly-risky surgery at the end of last year in California
Eva has a large intestine, a small intestine and a colon. Erika has a small intestine but no more in her digestive tract. It is not clear how doctors separated the uterus.
They have one leg each, and have learned to move themselves around using wheelchairs. Within a year, doctors believe they will be able to stand and walk with a crutch.
The girls were discharged from Packard Children's Hospital a couple of months after the surgery - Erika on February 13 and Eva on March 9 - before heading to a rehabilitation center, closer to their home in Antelope, California.
Now, they are at home with their parents Aida and Arturo Sandoval, and life, they say, seems completely normal.
'Having them separate, it's like the day-to-day for anybody with twins,' Aida told the Sacramento Bee. 'It's a wonderful feeling, just to be able to make sure two more little babies get to adulthood.'
Speaking of Erika, she told the newspaper she was delighted about her progress: 'She's her own person. Before it was just whatever her sister was doing. I love just watching them, learning their interests.'
'I'm definitely thankful that things turned out the way that they did,' she added. 'I know they're here with a purpose, they've made it this far. And what the future holds for them is just enormous.'
Moving on: Mother Aida (pictured with Eva, left, and Erika at home in Antelope) says their life as conjoined twins is now a distant memory
The girls have one leg each, and have learned to move themselves around using wheelchairs. Within a year, doctors believe they will be able to stand and walk with a crutch
The girls have participated in play therapy to help them adapt psychologically to the separation.
'Neither girl seems to have trouble adjusting,' said Packard Children's child psychiatrist Michelle Goldsmith, MD, who has worked with the sisters. 'They're both rolling with what's going on very well.'
As infants, Erika and Eva required tube feeding. They still receive most of their nutrition via nasogastric tubes.
Before separation, the twins' anatomy was like that of two people above the sternum, gradually merging almost to one below the diaphragm. They had a total of three legs, one of which was unlikely to ever be functional.
Tissue from the third leg was used as part of Erika's reconstructive surgery, meaning that each twin now has one leg.
Because they each lack some pelvic bones on the side without a leg, it is unclear if they will be able to receive prosthetic legs in the future. But whether they use prosthetics or not, physical and occupational therapy will help them gain more independence.
'Improving their functional mobility will be really important in getting them to continue adapting to their new bodies,' said Kelly Andrasik, an occupational therapist who has worked with the twins at Packard Children's.
'The specialized equipment that an inpatient rehab like Davis offers will really help them with this.'
Erika and Eva will continue to receive regular checkups with Hartman and other caregivers at Packard Children's despite returning home to Antelope.
'They're doing really well and they're ready to go,' Hartman said. 'It's a great thing for everyone on our team to see.'
LIFE BEFORE SURGERY
The girls started on their path to surgery years ago, as they began to suffer countless infections, and Erika was becoming dangerously weak.
On December 6, in one of the riskiest separation operations ever performed, the twin girls were successfully separated.
Their parents Aida and Arturo made the painstaking decision to attempt separating them last year, as it became clear that with every month more issues arose.
They had been hospitalized with dozens of urinary tract infections and countless cases of dehydration.
Aida was urged to abort the girls when she and