The country star's first husband Gary Chapman revealed all about his daughter's good deed in a Facebook post on Monday (23Jan17), asking fans to keep both women in their prayers.

"This is my oldest daughter, Gloria Mills Chapman," he wrote. "Tomorrow morning she is donating a kidney to her best friend, Kathryn. They’ve known each other their entire lives and when Kathryn was in need, turns out Millie was a perfect match. I’m so proud of her, words fail me. Please say a prayer for them both and trust, with me, that they are in His hands.”

He has since posted an update on the 27-year-old's progress, writing: "Millie is out of surgery and everything is looking good. She’ll be hurting for awhile but healing is underway. Kat is in recovery as well. Thank you all for your prayers and kindness. God is good."

Grant also shared words of support for Millie on Wednesday (25Jan17), adding: "We are so proud of Millie's selfless act of friendship, and are grateful that both girls are doing well after yesterday's surgeries."

Grant and Chapman tied the knot in 1982 and welcomed Millie, their second child, in 1989. The pair divorced in 1999. Grant is now married to Vince Gill, who she wed in 2000.