I've been caring and living with my mother for ten years, doing it all on my own financially and physically. I've given her a stable place to call home. My family never helped till last July when they took her for a visit and never let her come home. Now I'm going to court cause they want conservatorship and it's based on their lies saying I was abusing my mother's income. It's not true. I was getting paid to watch her and used all that income on her and our home. Now I'm left without a job, paying all the bills still and can't afford an attorney. I miss my mother and they will not let me see her. It's been a year. I'm so hurt and I know my mother is too cause the last phone call I had with her 4m ago she pleaded to come home. I've tried to get her and was lied to and my sister has brained washed her. It's hard, my mother never left me. My sister lives 3hrs away and it's getting harder for me to deal with this but I have no help at all.
This is a legal and legally binding action. Without a Lawyer you will not be able to act, and that is the simple truth in the matter. And without your Mother's protesting your Sister's action, your sister will surely get conservatorship. I am sorry, but these are the fact in the case.
I hope you will be able to nurture and support some relationship ongoing with your Mom and Sister if you find there is no way to fight this action legally. You say nothing about any nefarious intentions on your sister's part.....that is to say it does not seem to me that you consider her abusive toward your mother, or cruel, or intending to take your Mother's funds from her. Nor is your Mother currently complaining of being with your sister? That being the case I cannot see any way you can move forward in any action.
You might consider saving up the 350.00 or so it would take for an hour of time with an elder law attorney, taking all records you have of time spent with your Mom and of your expenditures and care of her as it is documented by you; that would at least give you a "legal opinion" and perhaps some peace of mind.
Most of these things, when they move into the legal realm, are beyond any opinion or advice a Forum can give. We can but wish you the best.