Fisher, 60, a longtime mental health advocate, openly discussed her battles with depression and bipolar disorder during her lifetime.
Prior to the service at the Hollywood Hills' Forest Lawn Memorial Park, despite the family's desire to lay both actresses to rest together, Fisher preferred cremation while Reynolds wanted to be buried.
According to USA Today, some of Fisher's ashes were placed in the coffin with her mother, with the rest residing in the Prozac pill urn that her brother Todd Fisher held during the service.
"Carrie would like that. It was her favourite thing, and so that's how you do it. And so they're together, and they will be together here and in heaven, and we're OK with that."
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He added that Friday's private service "was fitting and it was beautiful" and that the family was planning for a larger public memorial in the future.
Reynolds and Fisher's family held a private service at the actresses' home on Thursday, with Meryl Streep, Jamie Lee Curtis, Richard Dreyfuss and Penny Marshall among the celebrities in attendance.
Fisher died December 27, four days after suffering a cardiac episode aboard an airplane and Reynolds died the next day following a severe stroke aged 84.