I wouldn't

My mother, in her second marriage, had another child. I was already old enough at that point that it was conceivable for me to claim, when I was out walking her, that the child was mine.

Fast forward to the age where she's half my height and I have to hold her hand while we cross the street. I was babysitting her during the daytime all summer. After I had rolled out of bed and eaten, we'd usually go to the park, and maybe the mall. She didn't have any money, so it was browsing only. One of the stores has two floors, and the toys are on the second floor, so we'd take the escalator up. Whenever we came to the escalator, my sister, she'd grimace while backing away from it and hold out her hand to me, and hand in hand, we'd step onto the escalator.

Until the time I was already on the escalator. She wanted me to come back down, but I said I wouldn't. She'd have to get on alone, I said. She put one hand on the moving rail, one foot on the escalator, and stopped. She left her back leg on the ground as the front one was pulled further and further away from her. Boom. She hit the ground. Started crying.

She still talks about that day. One of the only memories she has of that summer.