my 15 years old step daughter

My boyfriend and I have an old baby boy that is almost 6 months. My stepdaughter is obsessed with babies and want to be the one to carry my son. She steal it from her brothers and sisters when they have my son. (I don't like the way she do that). She told me that she want a baby already and she is 15 years old. She is the crazy baby (chiflada) of my boyfriend. She also very jealous of my son and I don't see why. My stepdaughter lives with her mother. Does she has the right to be jealous?