I've been in your shoes with a couple of close family members, my friend. My Mom and my brother. There's nothing easy about it.
Mental illness is so hard to deal with. My older brother was hit with it in his early twenties...same with Mom...which is when it shows up in most cases. They, and we, had alot of rough years.
But to inject a note of hope, my Mom did much better in her later years, and today my brother is married and has two beautiful kids. There are still periodic struggles, health problems, and life is far from perfect, but he is a wonderful, warm, smart human being of great worth.
Yes, he relies on medication to keep things under control, but more importantly, he has faith.
The Rock of our salvation, Jesus, if you can get them to grasp on, is the stability they need to control their thoughts and emotions.
You and your beautiful daughter are in my prayers.
Amen.
God Bless you and yours.