You both need therapy, together and individually.

mrsconn23

Dear Prudence,

My parents found religion when I was 14. My younger sister and I went from having a normal childhood to being expected to be at church three times a week and give up any of our possessions for the good of the poor. Any gifts from friends and relatives were immediately taken away to be sold and tithe to the church. Then my folks got to be foster parents and started cramming as many kids as they could into our house. I managed to escape by joining the armed forces, but my sister suffered another eight years of the insanity until she moved in with her boyfriend. She later moved in with me after I got out and started my business. I have been very successful.

My relationship with my parents is frosty because they are committed to the idea that I didn’t earn any of it and it all came from God. So every time we speak they bang the drum that they are broke and need money for their mission or throw sob stories about my other “siblings.” It’s to the point I no longer take their calls. The problem is they keep getting through to my sister.
She is still somewhat brainwashed and wants to be close to our parents, so they use her as their mouth piece. I have repeatedly asked her to stop, but she continues. It is hard because we live under the same roof and it breeds resentment in me because I pay all the bills—including her school tuition. How do I talk to her?

—Earned It All My Own

banana468

You're going to need therapy but may also need to take a harder line and parent your sister.  Work with your therapist about this because it sucks all around but I would also not be OK financing someone's education to find out that their spare cash didn't go to help the household but to help people who will only ever make her feel less than. 

short+sassy

Therapy would be extra great for both of them, especially since there is resentment in their relationship.

It sounds like the sister has some kind of income, since she keeps giving money to the parents.  The LW should start charging something for rent.  Not more than what the sister can comfortably afford.  But so the parents can't get all of it and maybe it will help quell some of the LW's bad feelings with their sister.

Put the money in a savings account for her, just not one she has access to (obviously).  When the sister shakes the brainwashing, the LW can give the money back if they want to.  

I've read that when parents do that kind of thing with toys/clothes, it can be a seed that leads to hoarding when those children become adults.  Another good reason to see a therapist.