Hilary Duff Says 'Goal Is to Collect All' 'HIMYM' Stars After Neil Patrick Harris' 'HIMYF' Cameo (Exclusive)

The actress and her co-stars talk to ET about the OG cast members they have their eye on for future guest appearances.

Hilary Duff has high hopes that all of the original How I Met Your Mother cast members will eventually make appearances on How I Met Your Father.

After Cobie Smulders and Neil Patrick Harris reprised their roles as Robin and Barney on the Hulu series in the freshman finale and season 2 premiere, respectively, Duff exclusively told ET's Denny Directo on the set of HIMYF her ideal wish is to have the rest of the cast stop by. 

"I was really nervous to work with NPH. He's just such a stud. He's legendary," she said.

"Everything he does is, if he's hosting something or he's got a TV show on the air or he's doing Broadway, he's just fantastic. And so the fact that he said yes made us really excited," Duff added. "And obviously, our goal is to hopefully collect them all."

Duff confirmed she was the lone HIMYF cast member to work with Harris, joking, "I took him all for myself."

The 35-year-old actress and executive producer was joined for the interview by HIMYF co-stars Chris Lowell and Suraj Sharma. Lowell noted that the world HIMYF lives in is dynamic enough so that fans of the original series will appreciate the "Easter eggs sprinkled throughout" while new viewers unfamiliar with HIMYM can enjoy "a completely new world."

"We're lucky, man," Sharma said. "And this is to do with the casting, with each other, how we are as people. Everything is like we all vibe so well, right? But it is work."

"It's true," Lowell said. "To be able to come and work with people that you genuinely think of as friends like. They're it's an easy way to show up at work in the morning."

They already have their sights set on future OG HIMYM cast appearances should the stars align. Sharma shared that he'd like Alyson Hannigan return as Lily, while Lowell threw out Jason Segel as someone he'd like to see back as Marshall. (Segel, who currently stars in Apple TV+'s Shrinking, kept the door open for a possible appearance in the future, saying "I would do anything they ever asked me to.")

"Jason Segel, just because in my head he's like 17 feet tall and I just want that to be proven true when I meet him," Lowell quipped. 

"I think for me it would be Josh [Radnor] just because I feel like the similarity to the character... That makes the most sense storytelling-wise," Duff said. (Radnor, for his part, shared in an interview that he and Duff had discussions over email about the new show. He noted, "I wouldn't turn down an invitation.")

New episodes of How I Met Your Father drop Tuesdays on Hulu.