Billie Lourd has paid tribute to her late grandmother Debbie Reynolds on what would have been her 85th birthday.

The 24-year-old actress took to Instagram on Saturday (01.04.17) to share a sweet snap of her late grandmother - who died on December 28 2016 - stood beside her late mother Carrie Fisher, who had died one day previous on December 27, as she wished her ''Abadaba'' a happy birthday.

Billie captioned the photo: ''Happy 85th to my constantly classily clad Abadaba (sic)''

The post comes after her uncle Todd Fisher said he was amazed at how well she was coping after having to deal with ''two gigantic losses'' within such a short space of time.

Todd said: ''Billie is 24-years-old. She's dealing with two gigantic losses. These two girls - my girls, my mother and my sister, were big, big personalities [with a] big influence on Billie, myself, many people.

''There's a vacuum in the room and she's feeling it and we're all feeling it. It's just that I'm 59 and I have no choice but to step up and put this stuff forward. I'm letting [Billie] breathe, you know? She needs to breathe. She needs to step back from all of this loss.''

And the 59-year-old actor admits it was ''heart-wrenching'' seeing Billie have to deal with the devastating loss of both her mother and her grandmother.

He added: ''When I was standing in the room the day after my sister died and we're in the hospital and my mother was dying, I mean, I was more heartbroken watching my niece than I was for myself. It was heart-wrenching.

''The idea that somebody would have to deal with that kind of a loss back to back, moment to moment - I mean we'd just had this horrible loss and then here you are just a handful of hours later standing in a different hospital in a different room. It was astounding.''