Rob Schneider Celebrates Daughter Elle King's Pregnancy: 'I Know How Much You Wanted This'

Rob Schneider couldn't be happier about daughter Elle King expanding her family.

The Grammy-nominated rocker reveals in this week's issue of PEOPLE that she is pregnant, expecting a baby with her fiancé Dan Tooker. King's happy pregnancy news comes after she struggled with infertility and previously suffered two pregnancy losses due to polycystic ovary syndrome (PCOS), a condition that causes a hormonal imbalance.

Her father, Schneider, celebrated her pregnancy on Instagram Thursday, writing that he knows how much she wanted to become a mom.

"My dear Elle," the Grown Ups actor, 57, begins, "Words are insufficient for me to completely tell you how very happy I am for you and Dan on the news of your baby to be. I know how much you wanted this and how deeply you love your family. You make your sisters feel like every day with you is their birthday and Christmas."

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Schneider shares daughter Elle, 31, with ex-wife London King, and he's also dad to daughters Miranda Scarlett, 8, and Madeline Robbie, 4, whom he shares with wife Patricia.

"You have a special gift and I could not be more proud of you and I am filled with a happiness that only comes from the bringing of a new life into the world," he says. "God's gift and the universe's most perfect creation: a baby. As far as being a grandpa, that is still sinking in. And thank you."

"But it is the real meaning of relativity that comes to mind. Time and our relation to it," Schneider continues. "For me it feels as it was only this morning that I held you in my arms and first saw those sparkling blue eyes of yours. I knew that there was a very beautiful and powerful soul that had just come into the world. And soon there will be another joy to behold."

Schneider concludes: "The wonder of it all leaves me breathless and awestruck. For in your new child represents the hope of the world. And a reminder that God truly loves us. With all my heart, I adore you and I love you... Dad"

King, who is in her second trimester, tells PEOPLE that "every single day of this pregnancy is such a miracle."

"This is something that I have not only wanted since I could remember, but it's something that I have struggled with for a really long time," the "Ex's & Oh's" singer said.