It's been a busy few days for Harrison Ford. Not only did he nab fourth place on Forbes' list of the 10 Most Expensive Celebrity Divorces ever for his estimated $85 million payout to ex Melissa Mathison, but he's allegedly planning to take another trip to the altar.

At least that's the claim being made by Grazia magazine (via the London Daily Mail), which is convinced the AARP-approved action hero, 64, slipped a ring onto the now bulked-up finger of Calista Flockhart, 42, his low-key sweetie of five years.

According to the mag, the once and future Indiana Jones got down on one creaky but still relatively spry knee on April Fools' Day, and even recruited the "Brothers and Sisters" star's 6-year-old son, Liam, to assist with his totally hokey romantic question-popping plan.

"He coached Liam to run up to Calista and give her a rehearsed message -- 'Mr. Ford is going to be my daddy,'" says a snitch. "Calista just laughed but it was no joke. Harrison then told her he wanted to marry her. She's thrilled about the proposal and so is Liam."

Adds the picture-painting snitch, "Harrison knows after five years that Calista is the last love of his life. He's been telling everyone that it felt like the right time."

But to the immense disappointment of every prenup-specializing lawyer in Los Angeles, the discreet duo insists they have no intention of tying the knot.

"They are not engaged," Calista's flack pooh-poohs to Us, with Ford's echoing for good measure, "It's not true. They are not engaged."

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