sibelfie 

A selfie taken with a sibling, usually where both are making silly faces

Hey did you see the sibelfie that s_loves22 took with her brother on IG? That's a classic #sibelfie

sibelfie by Michaeljoshmc April 15, 2021

Simelfie 

Simultaneous selfie. Taking a picture of someone who is taking a picture of you at the exact same time.

We took a simelfie at the restaurant just now.

Simelfie by iSizzlechest June 13, 2014