Billy Joel and Alexis Roderick get married on Saturday, July...

Billy Joel and Alexis Roderick get married on Saturday, July 4, 2015, in a ceremony held at Joel's estate on Long Island. The ceremony was presided over by New York Gov. Andrew M. Cuomo. Credit: Myrna Suarez

Singer Alexa Ray Joel, 29, daughter of Billy Joel and his second wife, model Christie Brinkley, penned a poem she posted Monday on Instagram to commemorate her father's marriage Saturday to fourth wife Alexis Roderick.

"After six years of quiet yet unrelenting devotion / A surprise wedding sets their undivided promise in motion / I've never seen Pop more besotted yet contented / Nor his Darling, more luminously glowing / And, sufficed [sic] to say / On this glimmering gold-coast day / Many a tear on my hopelessly-romantic cheek was flowing . . . "

Billy Joel, 66, and Roderick, 33, are expecting a baby girl later this summer.

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