"This group of onesie clad supremely supportive humans (and many others #notpicturedbutinthepicture) are the kings and queens of my world," the Scream Queens star captioned the photo, along with the hashtags "#gratefulfortheirgreatness" and "#friendsfindingthefunny."
Lourd's boyfriend, Taylor Lautner, was also at the onesie party and appeared to be matching with the 24-year-old actress.
The two have been spending quite a bit of time together since Lourd's family tragedy. "This girl is one of the strongest, most fearless individuals I've ever met," Lautner captioned a photo of his girlfriend on Instagram. "Absolutely beautiful inside and out. I'm lucky to know you @praisethelourd."
"My mother's heart goes out to this exquisitely talented young woman,” Jamie Lee Curtis shared, who, like Fisher and Lourd, grew up as the daughter of Hollywood royalty. “Her mother's spirit and talent lives on in her and I'm sure all of Carrie's fans and friends will give her space and privacy.”
Here's a look at the sweet messages Lea Michele and Ariana Grande posted for Lourd: