Marvel rule #1: Make it personal. Taskmaster being the girl Nat thought she killed does this. Nat is the reason Antonia is a disfigured assassin controlled by Dreykov.
I would have changed it where Taskmaster is her daughter. What if they were taking these women's ovaries and creating women agents for the Black Widow program and the mom made a exception with Nat and instead used her ovaries to create Taskmaster. Maybe she is also part Super Solider which gives her the powers she has. From what I have heard that in the comics the Black Widows were not just regular women brainwashed and trained but also Super Soliders like Cap.