I do keep memories from my siblings.

My parents were harsher on me than my much older sister. Telling her my memories of mum backfired because for YEARS she insisted mum didn't treat her in X way, therefore mum couldn't possibly have done X to me repeatedly.

She kept defending mum because of her narrative that mum was harshest to her yet a "good mum" and therefore she wouldn't believe me.

Until this year.

My parents mellowed somewhat with my younger brother. So I don't tell him how they were harsher and more cruel to us older siblings. He was their favourite. And telling him might just hurt him because he has issues of his own.

I keep memories from the older brother too, because some of them involve him hurting me and he believes he never ever hurt me but helped me. He also firmly believes together with our older sister that the parents were worst to him, so I keep memories where they did Y to me but not him.