Félicité died of a suspected heart attack at her London apartment on March 13, at the age of 18.
She was an Instagram star with almost 1.3m followers, and an aspiring fashion designer who had last year revealed she was releasing a clothing range under her nickname, ‘Fizzy’.
A family source told The Sun at the time of her death: “Felicite was an absolutely adored young woman who was loved by Louis and her whole family.
“They are all totally devastated, as you can imagine.
“She had so many friends and was such a positive happy person. It’s a massive loss to the world.
“She was a loveable, caring, bright, passionate, popular and beautiful young lady.”
The X Factor UK judge was extremely close to his sister. They regularly saw each other in London.
Félicité’s death came after their mother, Johanna Deakin, died after a battle with leukaemia on December 7, 2016. She was 43.
Just weeks before his sister’s death, Louis paid tribute to his late mother in Two of Us — the first single from his debut solo album.
WATCH: Félicité Tomlinson's final interview before her death