My mother was always pretty demanding but also pretty giving. She has always carried an entitled attitude but again she's always been equally giving.
Since her dementia diagnosis she seems VERY narcissistic. To the point I'm starting to wonder if she's always been that way but maybe as a child I just never questioned it.
Similarly, dementia changes how the brain functions, so it can create a new persona never existed before.
This PD issue is with the person from a young age and ultimately anyone connected will be harmed.
Firm boundaries are required to protect your own mental health, shared care would be advisable with someone else understanding of this Personality Disorder.
Manipulative acts are very calculated and dangerous at times. Elders have rights and this behaviour could prompt you to reactive negatively. Take good care of yourself and hope this helps!