Hitler's Family: In the Shadow of the Dictator (2005)

Adolf Hitler consistently hushed up or denied his family lineage for fear that his ragtag bunch of ancestors and living relatives could tarnish his reputation or expose his imperfect Aryan background. His family had a history of psychiatric disorders, and his second cousin, Aloisia Veit, was locked up in an asylum for nine years before being sent to the gas chambers for being "unworthy of life". Hitler was embarrassed by his sister Paula, and made her live under the assumed name of Paula Wolf. Paula became engaged to Dr Erwin Jekelius, medical director of the asylum who sent hundreds of mentally ill patients, including Aloisia Veit, to their deaths.

Unfortunately the movie Hitler's Family: In the Shadow of the Dictator is not yet available on HBO Max.