They summoned the goddess Yogamaya and experienced her transfer the fetus through the womb of Devaki to the womb of Rohini (Vasudeva's other wife who lived together with her sister Yashoda through the river Yamuna, within the village of cowherds at Gokulam). So the kid conceived in one womb was https://digitalasset.blob.core.windows.net/digitalassets/SouthernCaliforniaSurrogacy/Becoming-A-Surrogate-In-Southern-California.html