I had a similar relationship with my sister, she sometimes treated me the way your mother treats you and it really used to p!ss me off.
For instance my sister must have learned in somewhere (which I have also since heard in Alanon) to always say I need to check my schedule before agreeing to something. But it got to the point where she would be coming over to see my kids and I would ask her to pick up toilet paper at the corner and she would tell me this wasnt what was planned.
What finally changed our dynamic was this instance.
She had invited me and the girls to sleep over her apt. in Manhattan a few months after bomb. I suggested she come to our place because it would be easier for us but she insisted so I agreed even though I knew it was too much. (She adores my girls which is awesome!) The next morning I needed to take the subway back to bklyn cause the older one who was 3 had school, the little one was just over 1 - I was carrying her in the baby carrier and pushing the stroller.
The morning, my sister had the day off from work, at 8am both kids started melting down. I asked my sister if she would ride the subway with me back to brooklyn. She said she couldn't (I think she wanted to go to the gym). My sister walked me to the subway with a screaming 3 year old and hysterical infant in the baby carrier and said bye.
From that point forward I stopped asking for help. After sharing about this at a Alanon meeting, I came to realize that i needed to stop going to her for any help and also not agree to do things with her & my kids where I would need help.
I stopped visiting her in Manhattan cause it was a schlep but she could visit us in broooklyn whenever.
In the 2.5 years since this happened my relationship with my sister has improved.
I stopped going to the hardware store for oranges and she started coming towards me more
---- M 39 H 35 D5,D4 M 4 T 9 ILYBNILWY 5/18/11 Left 7/11/11 Divorced 12/1/13