Photo: Katharine McPhee/Instagram

Katharine McPhee Shares First Photo of Son Rennie’s Face in Father’s Day Tribute to David Foster. https://www.instagram.com/p/Ce_rAgCp0-M/?hl=en. Katharine McPhee/instagram

David Fostercelebrated his youngest with a party based on his son’s latest obsession.

“He wanted the Power Rangers,” Foster, 75, tells PEOPLE of son Rennie, 4, whom he shares with his wifeKatharine McPhee Foster, 40.

“ThePower Rangerscame, and it was great,” he continues. “And we had a little bouncy house and some Mexican food and churros, and everybody had a great time.”

Foster says they were deciding betweenPower Rangersand Darth Vader, but eventually determined “Darth Vader might be a little scary for the 3 and 4-year-olds.”

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However, toddlers weren’t the only group Foster kept in mind when planning the celebration.

“These days, parents come to the parties too,” Foster adds. “So you find yourself entertaining the parents, thinking about what to do for the parents as well as the kids.”

Other than occasionally joining his parents on the road, Foster tells PEOPLE Rennie is “just a regular kid,” and he has dropped the drums since debutinghis skills at just 2 years old. Lately, Foster says Rennie shows a talent for puzzles.

“This morning, we were putting jigsaw puzzles together,” Foster shares. “I swear to you, I’m not lying. He’s better at it than me.”

Katharine McPhee/Instagram

Katharine McPhee and David Foster Take Son Rennie to Disney World for His 3rd Birthday

“We were just talking this morning, Kat and I, that we’d like him to go to the show, even though he’s too young, really,” Foster says. “But there’s nothing bad in the show for a child. It’s a really family-friendly show.”

In addition to Rennie, Foster is a dad tofive adult children— Allison, 54, Amy, 51, Sara, 44, Erin, 42, and Jordan, 39. He adds they all plan to support him onBoop! The Musical’sopening night.

“We just had a family dinner, and without me prompting, they’re like, ‘Yeah, we all want to be there on April 5,’ " Foster shares.

source: people.com