I'm so sorry to hear about the loss of your daughter! Also, I can relate to your story, because the child my partner and I fostered starting when he was an early teen was seriously addicted to THC when he came to live with us.
He already had multiple mental health diagnoses, and he struggled to heal. Smoking made his struggle much harder for a while. His addiction was understandable given how hard his life had been. He told us once that sometimes he felt the only comfort or pleasure available to him in life (because of his traumatizing circumstances) came from weed.
But weed was also damaging him badly. When he was only 13 years old, his entire life focused on where to find his daily smoke. And he didn't let much (or anything) stand in his way. We lived in Montreal, where weed was not legal but not exactly criminalized either. It was everywhere.
My partner and I had to stop smoking occasionally on weekends — so we wouldn't have any in the house, and so we'd be setting an example for him of how to enjoy life without being stoned.
As much as he had to recover from serious abuse and trauma, he also had to recover from addiction that made his trauma recovery even more difficult.
Before he came into our lives, I believed marijuana addiction was not possible, or if it was that it wasn't serious or dangerous.
But wow, some of the horror stories I could tell! I won't tell them, because they're not mine to share. They're private to him.
I'll just say that our teenage son showed us up close and personal that marijuana addiction can be intensely harmful, and very difficult to overcome.
Thanks for sharing your story, and again, I am so sorry for your loss! I can't even imagine.