I read the title and thought "Wow, if they can't tell the difference they have a problem!" :lol:
Mice stink, fish don't.
The kids need to get used to nature and the life (or death) cycle.
As Zev suggested, remove all the females.
You could also get rid of the live bearers. I know you said your danios spawned but, if I remember correctly, they weren't in the main tank at the time were they? (I might be confusing you with someone else)
My egg layers spawn in the tank too but the eggs usually get eaten and only one or two fry occasionally survive.
If you have a heavily planted tank and driftwood you can say the BNs are just hiding