Oh honey.
They say the teen brain isn't fully developed.
At times, I wondered if my teen even had a brain.
You had to be scared out of your mind, then sooooo ticked when you knew she was ok.
From the sounds of it "Adopted" and
"Birth Grand Mother" are words that sound like the birth mother isn't in the picture.
Being a teen girl in a "normal circumstances" are challenging, but add in the other stuff and it gets even more complicated.
Some say "Spoiled" some might say "acting out"
Regardless of what it is.
The behavior is unacceptably.
You sound like you are handling things with grace, discipline, and not feeding to sooth the problem.
Good for you.
You are doing great!
Prayers for you and your family.
Life is hard, but we will get through it.
(Hugs)