A Semi-official Description:
Luce:Luce is the original holder of the Orange (Sky) pacifier. Her name is pronounced as “lu-che” and it means light in Italian. She is the mother of Aria and the grandmother of Uni. She was a former leader of the Giglio Nero Famiglia. As of the time the Arcobaleno trials were conducted, her status and whereabouts are unknown. In the anime, she seems to have had a good relationship with Reborn and thinks Reborn's sideburns are his most attractive features. In Reborn's recollections, it seems that she has some power of foresight, enabling her to know beforehand the curse that comes together with taking care of the pacifier.
Aria:Aria is the former leader of Giglio Nero Famiglia and the 2nd Sky Arcobaleno. She is the mother of Uni and the daughter of Luce. In the Future Arc she was said to be dead due to an illness, most probably because Sky Arcobaleno are known for their short lifespans since she took on the curse. In Gamma's flashback, she and Gamma had a close Boss and Subordinate relationship (implied in the manga to be romantically intimate).
Aria was the one to administer of the Sky Trial. Her Trial involved Tsuna having to do everything she says without a complaint even to go far as protecting her from men possessing Box Weapons, without knowing if she herself was an enemy. In the end, Tsuna obtains the Sky Seal after completing the Trial of tolerance.
During Verde's Trial, she leaves Gamma to watch over Kyoko, Haru, Futa, and Nana Sawada.
Uni: Uni is the daughter of Aria and granddaughter of Luce. She is a young girl who is the Millefiore Family's former Second-in-Command and the former Leader of the Giglio Nero Famiglia as a result of the early death of her mother, whom she did not know was a Mafia Boss. She inherited the Orange Arcobaleno Pacifier from her mother. This Pacifier has been passed down in their Family for three generations. When Aria passed away, she learns of the Mafia and the leadership role she must play for the Giglio Nero Family. Uni was originally kindhearted and caring towards others and during that time she came to know Reborn whom she knows as her Uncle. The Giglio Nero Family was losing strength and power. In order to keep the Family's power, she meets Byakuran who schedules a meeting with her. After the meeting, Uni emerges from Byakuran's office with a completely different attitude and personality (Acording to Shoichi her heart was dulled with a powerful drug). She then announces that the two Families will merge and become the Millefiore Family. As a result of the merge, she has become bitter, and cold hearted. She is now the head of the Black Spell and Captain of the 1st Calendula Squad.
After the first round of Choice, she had recovered from the drug and intervened to say that the promise that Shoichi said that they made is valid and Byakuran should honor it. When Byakuran ignored her suggestion she decided to leave the Millefiore Family and asked Tsuna to protect her.