Cast members photographed filming together: Gaten Matarazzo, Sadie Sink, Joe Keery, and Maya Hawke
Nepotism Things, Part Deux
Also seen on set was Maya Hawke's brother, Levon. Fans are speculating that he may be playing one of the new high school characters. I think this will probably be more in line with Shawn Levy's daughters popping up as background actors in the show, but I'm also hoping that's all this is lol.
Sources: 1 2 3