Lourd, who lost Fisher and Reynolds just one day apart, had yet to speak about the double tragedy until now.
"Receiving all of your prayers and kind words over the past week has given me strength during a time I thought strength could not exist," Lourd wrote next to a photo of her with Fisher and Reynolds. "There are no words to express how much I will miss my Abadaba and my one and only Momby. Your love and support means the world to me."
Lourd is Fisher's only child. She is the daughter of talent agent Bryan Lourd, who was with Fisher for three years from 1991 to 1994.
Fisher suffered a heart attack aboard a flight from London to Los Angeles on Dec. 23 and died at the hospital on Dec. 27.
The next day, Reynolds suffered a stroke while at son Todd Fisher's home in Beverly Hills planning the funeral arrangements for her daughter. She died that day. Todd told the Associated Press his mother's last words were, "I want to be with Carrie."
Since the deaths, Lourd's Scream Queens co-stars have showered her with love and support, including her rumored boyfriend Taylor Lautner.
RIP, Debbie Reynolds and Carrie Fisher. Our hearts go out to Billie Lourd and family during this difficult time.
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