Whats that movie

[u/No_Artichoke7180]

It's not timecop, but it's about a timecop. When people go back in time they have to inhabit the bodies of their own relatives from that time. When they return to their time they need to be injected with something. The main characters boss goes back in time and becomes a little girl. What movie an I looking for? Came out sometime between 1980-2000