Ygabba Hise is the daughter of Gab'borah Hise, the old man who befriended Boba Fett onboard Jabba The Hutt's sailbarge. When the two first met on the streets of Mos Espa, Boba had been fleeing from Durge. Ygabba and Boba did not get off to the best start in their first encounter as Ygabba had stolen Fett's helmet after it had fallen off. Boba chased her down one of Mos Espa's alley ways where he was attacked in a dark shed by one of her accomplises. Her accomplise turned out being one of several street kids including Ygabba who had been left to fend for themselves until they were "rescued" by a Neimodian named Gilramos Libkath. Libkath used the children to steal weapons and other items from Jabba the Hutt and then resold them. Ygabba and the others were forced to carry out Gilramos' schemes or risk punishment or worse off, death. To control the children and keep any from escaping him, Gilramos had them outfitted with a cyber-organic device that looked like a glowing red eye in their hands. The device was designed to release a deadly neurotoxin should any of the children ever leave off world. With Boba's help Ygabba and the children were able to escape the control of Libkath and find their way back to their parents or relatives. While accompaning Boba back to Jabba's palace, Ygabba found herself unexpectedly reunited with her own father, Gab'borah, the old man who had recently befriended Boba Fett. With father and daughter once again reunited thanks to Boba, the bounty hunter gained two loyal friends, something which he hadn't many of.
Source: "Boba Fett - Hunted" by Elizabeth Hand