Hilary Duff and ex-husband Mike Comrie celebrate son's birthday together

Amicable exes Hilary Duff and Mike Comrie continued to show what co-parenting is all about this weekend when the former couple reunited for their son Luca’s 4th birthday.

“We are so proud of this boy!” Duff captioned a sweet family photo with her little boy and Comrie.

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Earlier in the day, the "Younger" star shared a sweet pic of her son eating birthday cake to Instagram, writing, “You….are magic my little big boy. Happy 4th birthday. My heart just explodes for you.”

The whole family got together to celebrate Luca’s birthday with aunt Haylie Duff sharing an adorable photo with Hilary, Luca, and her daughter, Ryan.

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“Celebrating my sweet nephew Luca today! I can’t believe he is 4! #HappyBirthday to the sweetest boy & best big cousin. We love you Luc! (also Ryan has a huge mouth full of food in this pic haha),” Haylie captioned the pic.

In February, Hilary and Comrie finalized their divorce, more than two years after they announced their separation. A month earlier, the Disney Channel alum opened up about her relationship with the father of her child.

“We have such a great kid, and we’re both so obsessed with him,” she told Ellen DeGeneres at the time. “We are good friends and we laugh a lot, and we have a great communication.”