"Tom is thrilled to be walking Meg down the aisle," an insider told Radar. "He thinks of her as family and has a real soft spot for John, too!"
The When Harry Met Sally actress, 56, and the 66-year-old rocker first got together in 2011 but split up three years later. They dated again briefly in 2015, and when that fling ended, it seemed final.
"She hates me to death!" the "Small Town" singer told Howard Stern in 2017.
But now they seem happier than ever — and Mellencamp's neighbors in South Carolina believe he's making plans for a big fall wedding.
That left one huge question: Since Ryan isn't close to her own family, who would walk her down the aisle? Of course, Hanks came to the rescue.
"Tom's filling that void, almost like an older brother," the insider revealed. "Meg adores Tom and had no hesitation asking him.
"This will be a loving, spiritual ceremony where she and John can proclaim their commitment to each other, surrounded by the people who matter to them most."
We pay for juicy info! Do you have a story for RadarOnline.com? Email us at email@example.com, or call us at (866) ON-RADAR (667-2327) any time, day or night.
Get the exclusive celebrity scoop on all the stars you love before any of your friends by subscribing to our new podcast Straight Shuter below!