The female twins, named Lydia and Maya, were born eight weeks premature at the Inselspital hospital in Bern, along with a triplet who was fully separate and healthy.
The twins are now recovering in the pediatric intensive care unit, but doctors expect them to recover from the operation.
They join about 200 other separated conjoined twins currently living around the globe. Also known as Siamese twins, conjoined siblings are seen in about one in 200,000 live births.