Maddy Cusack's family says Sheffield United have agreed to a full external inquiry into the events leading up to the midfielder's death.
Cusack, the first player to reach 100 appearances for the Blades, died in September at the age of 27.
Police did not treat her death as suspicious.
In a statement via the Maddy Cusack Foundation on social media, her family said Cusack's spirit had been "broken" in the months before her death.
"From February this year, the indomitable, irrepressible spirit, the spirit called Maddy, the spirit that we had so fiercely protected, was allowed to be broken," the statement read.
"Those who knew Maddy well will be aware that she had no long-standing mental health issues or troubles. Not that there would be anything to be ashamed of if there were, but there were not. Those that didn't know her need to know that.
"Maddy was a happy-go-lucky, carefree girl with everything to live for and by last Christmas could be described as being at her happiest. This all changed gradually from February this year.
"It is no secret, nor should it be, that Sheffield United Football Club have agreed at the request of Maddy's family to carry out a thorough external investigation into the events that her family believe contributed significantly to her passing at the tender age of 27."
Sheffield United declined to comment when approached by BBC Sport.
An inquest into Cusack's death was opened last month and adjourned, with the medical cause not yet established.
Cusack, who also worked as a marketing executive at Sheffield United, joined the Women's Championship club in 2019.
At the time, the club said they were "devastated" by her passing while men's manager Paul Heckingbottom said Cusack was a "big part of everything" at the club.
Tributes were paid at football matches across the country following her death, including at Sheffield United women's and men's games, and England's fixture against Scotland.
Cusack previously played for Birmingham, Aston Villa and Nottingham Forest.