Hey there @Becca3017
First off — I had to make a quick edit to your post to remove the specific types of self harming you described. Reading any kind of specifics can sometimes be a trigger for those overcoming self harming behaviour.
It sounds like it's a very stressful situation for you to be in.
Being that ReachOut is primarily focused on young people and their experiences, we might be a bit lacking on members who are parents and have gone through something similar, however, if a member wants to share their experiences as a family member that has been in a similar situation, hopefully they will post soon.
Everyone copes with things differently. Your daughter and stepdaughter each have their own sets of challenges and the way they cope with them is inevitably going to be different as a result.
While your stepdaughter is overcoming her self harming behaviour, seeing your daughter engaging in self harming could have been very frustrating for her if she's struggling to cope with getting through it herself. It may have been triggering in some way, too, which might have been difficult to handle.
That said, violent and threatening behaviour is never acceptable. Did you let her doctor/psychologist know about it? It could be important in terms of any medication she might be prescribed.
