Q. An individual that comes to our shul suffers from a Multiple Personality Disorder. Although he can basically take care of himself, we are not sure if we should give him an aliya or even count him as part of the minyan. What is Horav Miller's opinion?
A. Dissociative Identity Disorder, as this mental health condition is also known, represents the one having two or more separate personalities. These identities control a person's behavior at different times and to a degree is surprisingly quite common. This shaila is addressed widely for many situations and by many Poskim.
Horav Shlomo Miller's Shlit'a opinion is that for the purpose of counting him for minyan and giving him an aliya, it suffices if he legally can sign a document or a cheque and it would be valid.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit'a