Paint Tool Sai 2: Downloading & Add Scatter Brushes
I haven't had a problem adding new brushes, and I had a couple comments unsure why it's not working for them. So, this is how I do it and I really hope it helps you all out!
Frenny's Dream : Found another solution if you're having issues and my way doesn't work.
Folder SYSTEMAX - SAIV2 - settings - brushform - brshape Add the file to this last folder