They could make impostors able to shape shift. so when they kill a player they can steal their color and username. But you can only shape shift one time per impostor. so its not too op
Maybe they could make it to where they could kill, and they take that persons body for about 5 seconds for a quick get away. And the body is gone for those 5 seconds
And i think another good option is for when an impostor looks on the map they can see where their partner is so they're not just looking for them the whole game