Shortly before World War I, Renié became friends with the family of one of her students, Marie-Amélie Regnier. After winning the Premier Prix and being introduced to Théodore Dubois, Marie-Amélie swore that Renié would be the godmother of her first child. During the war, Renié undertook the family's financial support. When the war was over, Marie-Amélie got married and presented Renié her goddaughter, and because Marie-Amélie's husband, Georges Pignal, was an engineer who was frequently absent because of contracts in Morocco, the child spent more time with her grandmother and godmother than her parents. In 1923, Renié helped Louise Regnier (Marie-Amélie's mother) buy a portion of a house. She moved in with the Regniers, along with her brother François, shortly after her mother died. In 1934, Louise Regnier died and left the goddaughter, Françoise, in Renié's devoted care. Sometimes, Renié would ride in back of Françoise's motorcycle. Despite Marie-Amélie's former gratitude and Renié's generosity to the family, the former pupil was a hostile housemate and tried to evict the Reniés, but Françoise fought her family to save Renié from financial ruin.