"Christopher and Jay, they're a different relationship," Biggie's mother Voletta Wallace told ABC News. "They're very good friends."
Wallace, 64, is featured in the two-part A&E documentary, "Biggie: The Life of Notorious B.I.G.," which premieres tonight at 8 p.m. ET. It centers on Christopher "Biggie" Wallace's legacy and impact on hip-hop culture. His widow, singer Faith Evans, and rapper Lil Cease, are also featured in the first biography authorized by his estate.
"So usually I just [say], 'Get JAY for me, this is what they want to do.' And he was always there," Wallace continued.
Wallace said JAY-Z was one of her son's biggest supporters, who was always willing to go the extra mile for him. In fact, the rapper always made himself available to honor his friend -- even with his new twins on the way.
Wallace said initially the media mogul's involvement "was a little iffy, but when it comes to Christopher he will...say yes."
In addition to JAY-Z, the doc will feature commentary from Nas, DJ Mr. Cee and Sean “Diddy” Combs.
Wallace said Kim's absence was due to scheduling conflicts, and she would have "loved to have had her be part of [it]."
Faith Evans agreed, saying everyone was on board to bring this doc to life -- especially with Biggie's mother involved.
"I think with all of us kind of coming together and being a part of helping them make this film happen, I don't think it was hard at all," she explained. "I mean, obviously you got to work around people's schedules, but I think some things only take a call from Ms. Wallace sometimes."