I don't want to give up personal sentimental objects to our grandparents
Why do you think I will agree to your idea?
Because I think it is our parents and grandparents who gave us things and I don't think they deserve anything for that.
You need to respect your elders though, they are very vulnerable and just want some bonding time with you. It is important to share these experiences and objects to create good memories while they are still alive. You shouldn't be left with nothing when they pass.
How does that matter since I'm alive? And for starters, I have nothing to give and no one to give it to anyways.
You can always find things to give even it if is time. Family share things with each other. If you are selfish, they might not want to give you things anymore.