Hi
Daisy May!
Welcome to our site and online family! You sound like you could use a hug.
I am thankful that you are there for this little one, and that you know how much she needs you. Thank goodness and kudos to you for doing your best.
How long did you say they have been living with you?
A couple of questions for you. Are you in T for yourself? I would strongly suggest it to help you, and one really important thing is to remember that you must be kind to yourself so you don't burn out. You are shouldering a lot of burden right now. Is the dad in the picture at all or financially responsible?
It is tough to walk that line between love, enablement and grace. If you could do what you want to do in this situation without worrying what your sister wants or needs, what would that look like to you? Have you tried any boundary setting in the past?
There are so many other members here who struggle daily, just like you. My mom was an uBPD. I struggle daily as I recover from that, and I'm making great progress. You seem pretty aware, and that will be such a help to you.
Looking forward to hearing more!
Wools