The 24-year-old, whose real name was Chris Hardman, was found dead in Lowestoft on Monday.
Fellow musicians and fans paid tribute on social media to the singer, who rose to fame in Channel 4's Rock School.
Hannah Hardman said: "Please keep them coming. They are helping the family at this difficult time."
Suffolk Police said it was called to an address in Union Road on Monday morning to reports a man had died suddenly.
The force is not treating the death as suspicious and a post-mortem examination is due to take place.
Kiss bassist Gene Simmons, who tutored Hardman during Rock School in 2006, took to Twitter to express his sadness at the death, saying his former pupil "was loved".
After playing in front of 20,000 Judas Priest fans in LA as part of the programme, Hardman launched his solo career with the single Checking It Out.
He recently moved into theatre and appeared in Loserville, which was written by McBusted's James Bourne.
Bourne and his band paid tribute to Harding during Tuesday night's gig in Sheffield, calling him a "good friend" and "lovely guy".
The band played a cover of Beastie Boys' (You Gotta) Fight For Your Right (To Party!) in his memory.
Tributes have also been paid at Hardman's former school, Kirkley High School, where Rock School was set.
Pete Seadon, assistant principal at the school, which is now called East Point Academy, taught Hardman PE.
"What has happened is a real shock," he said. "There are staff still here who taught him.
"He was well-known and well-liked and a talent that has come from the town."
Tributes to singer Lil' Chris have brought "a lot of happiness" to his family, his sister has said.