Maddy Cusack's family says Sheffield United have agreed to a full external inquiry into the events leading up to the midfielder's death.
The 27-year-old, who was the first player to reach 100 appearances for the Blades, died at her home in Derbyshire in September.
Her death was not treated as suspicious by police.
In a statement posted by the Maddy Cusack Foundation on social media, her family said Cusack's spirit had been "broken" in the months before her death.
It said: "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.
"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 have declined to comment.
Cusack, who also worked as a marketing executive at Sheffield United, joined the Women's Championship club in 2019.
Speaking exclusively to ITV News, Cusack's younger sister, Olivia, previously described her death as "extremely difficult".
But she said the family had taken great comfort in the support of fans, both in person and on social media.
Shortly after Cusack's death, the family announced plans to set up the football foundation in her honour, aimed at encouraging girls to take up the sport.
Cusack's brother Richard said that the foundation was a way for the family to cope with her death, adding that the "best way" to honour his sisters' legacy was to "inspire young girls to play football".
An inquest into Cusack's death was opened last month and adjourned, with the medical cause not yet established.
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