Cissy Houston arrived at the bedside of granddaughter Bobbi Kristina Brown late Thursday, and hasn't left her side; Meanwhile, Nick Gordon has not returned to visit her in days -- get all the exclusive details from Us Weekly. Credit: Shareif Ziyadat/FilmMagic

Grandma's here. Flying in from her native New Jersey, Cissy Houston, the mother of the late Whitney Houston and grandmother to the ailing Bobbi Kristina Brown, has arrived at Emory University Hospital in Atlanta, and is at her granddaughter's side as the music scion remains in a coma, Us Weekly can exclusively reveal.

Meanwhile, both Brown and Houston families have congregated in Atlanta, where they await updates on Bobbi's condition. A source tells Us that Bobby Brown and members of his family have been in and out of the Intensive Care Unit of the hospital, where they have been meeting for prayer group.

The insider adds that Bobby and the whole family have either been by Bobbi's side or in a larger room where they have been praying and singing hymns. The source tells Us that dad Bobby has specifically been singing hymns to his 21-year-old daughter as she remains unresponsive.

Another source tells Us that the sleep-deprived father has been ordering coffee around the clock as he tends to his baby girl.

Bobbi's first cousin Jerod Brown addressed her condition in a Facebook update on Thursday. "Though it seems the odds are against her," Jerod, the son of Bobby's late sister Bethy, wrote. "STILL PRAY FOR BK." Us also confirmed Friday that two family members on Bobby's side of the family — Tina and Shayne Brown — had gotten into a brawl at a nearby hotel early that morning.

While most of the family remains steadfastly by Bobbi Kristina's side, another source tells Us that her longtime love Nick Gordon has not been to Emory at all since his initial visit to North Fulton.

"Nick hasn't been to visit Bobbi since she moved to this hospital," the insider reveals to Us. "I think he's banned from seeing her. Nick spent the entire first day with her, but hasn't been back to see her."

Bobbi was found unresponsive and facedown in her bathtub in her home on Saturday by friend Max Lomas. When paramedics arrived on the scene, Gordon was performing CPR on his alleged wife. It was revealed later that Bobbi and Gordon were not married.