What do you mean by "treat her" ?

only her treatment providers can take care of her mental disorder problems.

if you mean treat her as in how you should act around her... act the same way you have been since the day she was born. she is a human being. the mental disorder just names what has already been happening since she was under the age of 5 yrs old. so treat her like the sister she is, and the sister you have always known.

you mentioning you ***think*** she may have DID isnt going to do anything., especially since she hasnt been diagnosed by a professional and she doesnt believe such a diagnosis exists..

leave the diagnostic discussions up to her treatment providers. and be the sister which is your relationship to her.

by the way just because you have read up on a mental disorder and ***think*** someone has that does not mean they do..

example I know someone who went online and believed those who were not their treatment provider when they told him his symptoms were DID.. that guy is now dead because he had cancer. the cancer way making him dissociative, appear to have different personalities taking control, having memory problems similar to that of dissociatve's.

my bringing it up to her and trying to get her to believe in the diagnosis could ultimately kill your sister if DID is not why she is having these symptoms you ***think*** she has.

my suggestion leave her mental health issues up to her to deal with and be a sister to her. if at some point she feels she has a mental problem she will contact treatment providers who will then diagnose her problems and treat her for them.

trying to diagnose friends and family usually ends up with disastrous results, as does trying to confront someone who does not believe they have that problem family and friends are telling them that they have.