"This is how you will love me."
That's the answer that Eugenie Smet received when she posed the question about how to help the souls in Purgatory. She was a French woman, daughter of a prosperous couple whose reversal of fortune recalled Eugenie from a boarding school to her family's home outside industrialized Lille. Upon discovering the plight of the poor, Eugenie dedicated herself to alleviating it. She took apples from her father's orchard to give the needy. She collected money for the missions in China. Eventually, she dedicated her virginity (didn't they all!) to God. And when she heard about the souls in Prugatory, she wanted to help them too.
Frustrated by the priest under whose care she was initially placed, but encouraged by the archbishop of Paris, she opened a house for women who shared her aspirations. Though deeply in debt, they began to make a go of it in Paris, but still did not know how best to help the souls in Purgatory. Then a woman knocked on her door, asking if she and her sisters could help a sick woman who refused to admit a nun or priest. The answer came to her through an inner voice: This is how you will love me.
From then on, the women working with Eugenie, who had taken the name Mary of Providence, dedicated themselves to comforting the urban poor of Paris. They struggled against alcoholism and prostitution, providing what help they could to the needy and the sick, all the while preaching the Gospel in gentle and inviting fashion. They dedicated their work to the souls in Purgatory in hopes that the dead might benefit from the good works of the living.
I don't know about the efficacy of dedicating their work to others, but I do believe that the Creator speaks to individuals through an inner voice, and that those blessed individuals who hear the Creator will understand what is required for their salvation.