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Once family, always family.

Shortly after Billy Joel broke the news that his mother, Rosalind Nyman Joel, had died on Sunday, his ex-wife Christie Brinkley penned a touching tribute to her former mother-in-law.

Rosalind, the inspiration for Joel's song, "Rosalinda's Eyes" from the 1978 album "52nd Street," was 92.

"At sad times we look for ways to find the good to lift our spirits, So I have only to imagine what Rosalinda's Eyes have seen to find cause to celebrate a life well lived !" Brinkley posted on Instagram Tuesday, alongside a picture of Joel's mother as a young woman.

"Just in this year alone she saw her son, Billy Joel receive the Kennedy Center Honor, the highest cultural honor possible, from the President of the United States no less, and Rosalind greatly appreciated the Arts!) She also saw her son get a regular gig at Madison Square Garden ( where he already holds a record and where Roz is welcomed on a first name basis!" wrote Brinkley, who was married to Joel from 1985 to 1994.

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Brinkley also mentioned her only child with Joel, Alexa Ray Joel, and how proud Rosalind was of her granddaughter for following in her father's footsteps.

"Her eyes sparkled with pride and joy as the former Gilbert and Sullivan chorus girl, watched her granddaughter Alexa perform at the famed Cafe Carlyle surrounded by a large group of her friends enjoying themselves," Brinkley wrote. "I know as a mom myself that when you see your kids happy healthy and enjoying their passions you feel content and happy."

Brinkley concluded with, "Rosalinda's Eyes will live on not only in the song inspired by her, but in Billy, and Alexa… and Nanny Roz herself would find that worth celebrating. @alexarayjoel#cherishedgrandmother #restinpeace"