Does she need to help or not?

I have a sister who is married she is 57 ( no kids) Her husband is a family judge and ears good money, my sister does nto earn as much as him but she has a salary. Of course as a husband and wife they have their house and personal expenses. But still they both enjoy socializing , they travel each year overseas, they pay a diet plan (those are pricey) and they fo coruse sher house utilities and othre house expenses but yet my sister does not pitch in to help with some things for our mom. My mom is an elder person aand me and my brother take care of her at home. Our dad passed away 10 years ago, so now my mom support are my brother and me. My mom receives a monthly pension for the house expenses of course.

Anyway my sister always tell me and my brother thatn when it is health related issues for mom, we can't be picky, we pay for what we have to pay. In regards of that. My brother and I manage a savings accoutn for mom for extra expenses for mom (this is different than my mom pension). SO my sister is aware of this money and because of that if my mom lets say for example will ned some treatment, or we need to buy her things for her, my sister say we have to take money from this savings account. But my sister even if it is a expense for mom, my sister does not help one bit in at least helping with some money if we need to buy mom something. She says that is what the savings account is for. But hey at some point wwe can ran out of these savings but my sister never help at least with something financially so the burden can be at least shared by 3 not just one.

Some say my sister is not in the obligation to help if the money we have is my mom money. I mean regardless if my mom has money to afford certain things, common she is her daughter she could pitch in in something and help if needed.

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I mean she has money to travel, to pay diet plans, to go out socially with her husband. but then if we ask her for money tor mom, she always come up with an excuse. liek she does nto have a lot of money.
Does she need to help or not?
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