AfterLife (2003)

High-flying journalist Kenny Brogan (Kevin McKidd) is working on the story that could make his career when he is told his mother is terminally ill. With his father no longer in the picture, this means that the responsibility for looking after his Down's Syndrome sister Roberta (Paula Sage) falls to him. Conflicted by career aspirations and the difficulties in caring for his sister, Kenny at first begins to resent Roberta, until he realizes just how much she means to him.

Unfortunately the movie AfterLife is not yet available on HBO Max.