Same relation as a stepsister, but with positive connotations as opposed to the negativity that is typically associated with a Stepfamily. Bonus family members are chosen freely and they enrich your life.
My mother remarried after I moved out of the house. I am a good friend with her new husband. As an added bonus, I was introduced to an awesome new awesome friend: my Bonus Sister.
by DieDirk May 7, 2016