The actor, 55, and wife Christine Baumgartner Costner "are expecting in June," rep Arnold Robinson confirms to PEOPLE.
The new arrival will join older brothers Hayes Logan, 13 months, and Cayden Wyatt, 2 ½ – his sons with Christine – as well as Liam, 13, Joe, 22, Lily, 23, and Annie, 25, his children from previous relationships.
• Reporting by JULIE JORDAN
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