stepbestie 

A cross between step-sibling and bestie. Just to go that extra mile and show them how much you appreciate them. Can be used as a gender neutral term.

Person 1: Who's that?
Person 2: That's Goose! They're my stepbestie.

stepbestie by object_lover03 June 26, 2023

Stepstie 

Your exes old bestie, is now your bestie. No strings attached cuz it would be messy but u can love them forever and have each others backs.

I met you thru her and you're her bestie now we're broken up and you're my stepstie.

Stepstie by Humbwoi June 19, 2024