Is it appropriate younger siblings see fresh cuts?

My daughter has been cutting herself for the past 18 months. She has been seeing a therapist and things have steadily started to get better in terms of a marked reduction in her aggressive outbursts and the frequency that she self harms. Recently she cut herself all the way up her arm and is making no attempt to hide the cut marks. I am finding it difficult to see them and still struggle to understand why she is doing this to herself. Is it common that someone who self harms shows the cuts so blatantly when in the home. Maybe I should take some solice that she feels safe enough to not hide them, but I do worry that her younger siblings are also seeing the marks. Personally I do not think it appropriate for her siblings to be exposed to this. Do I ignore it or do I ask her to cover the marks up so that her younger siblings are not forced to see them? Has anyone else experienced this, can anyone offer any advice