Hello all this is my first post here. After watching the 1st episode again I felt that Sabrina must have been in Aliya's fathers's life. Maybe as a patient or as a fellow doctor or maybe even as a love interest. She could have looked different and probably used a older woman's body. She only injects venom in people she needs to help fulfil her plan. Like Mohit. The rest she kills within a second and takes their heart.
And it's possible Aliya never even heard of Sabrina because she only saw her father in hospital when he was in a critical stage and she was crying wondering what happened to him. Maybe she was in a different city.