My nan refused to let my mom have her engagement ring saying it was for me. So my mom demanded that all other jewelry be given to her. My nan then said, well the heart ring goes to Ashley *my sister*. My MOTHER is mad because we *her daughters* are getting one ring each. My papa laughed at my uncle and said "ok tell ya what, you can have the record collection and the girls will get the house".......my uncle and my mom lost their minds at the thought. So they shut up a bit. I know it's sad but common for these types of things to happen. I just hate seeing it happen to people I love by people that are suppose to love them. In the end I'm just going to continue to help my grandparents the best I can. It's just driving me a bit nuts not to tell off my mom or anyone else that deserves it.
I understand, your natural reaction is to lash out, but like you say you dont want to stress your nan out anymore. Its hard to believe that people who are supposed to be family are only worried about what they're going to get at the end, but as i say, this is a regular occurance.
Stick to you guns and help your nan and papa out, at the end of the day, you wont have any trouble sleeping because you've put yourself out and done all you can to make their lives a little easier. There will come a time (and there will) when people will look back and question themselves about how they acted and if they could have done more to help...you wont tho, you can hold your head high.