If I'm understanding what you've posted correctly, the 10g tank was set up less than 3 weeks ago (no longer). You used the water from the 5g (plus fresh I assume to make up 10g). You put the surviving danios in the 10g and more died until two were left. You then added 6 new fish.
I'm afraid it is very obvious what happened; the 10g tank was not cycled. It takes 2-8 weeks to establish the nitrogen cycle. Had you not added the new fish the two danios might have survived and cycled the tank.
I recommend you read the sticky on new tank cycling, here's the direct link [it is at the head of the Freshwater Aquarium section]: http://www.tropicalfishkeeping.com/f...m-cycle-38617/
Second comment I have is never add chemicals to a tank with fish unless they are absolutely essential. And when there are obvious problems (fish dying) adding any chemical is likely to worsen it since these stress out fish and the fish are already under stress from the health issue or whatever. Water conditioner is the only substance we need to use regularly. Other additives may or may not be advisable.
What water conditioner are you using?
What exactly is the "stabilizer" stuff?
Is anything else being added to the tank?
When I know the above, I should be able to offer more.
Another quick thing, your selection of fish is not good because you have fish that require quite different water parameters. "Compatibility" in a community aquarium is more than just behaviours; fish must share the same basic requirements concerning pH, hardness and temp; and the same environmental needs (things like wood, rock, caves, plants, etc). Livebearers are basic/hard water fish; tetras are soft acidic water fish. There is some adaptability, but these two extremes should not be combined. We can go into this more later, first let's get the immediate problems solved. It goes without saying, do not buy any more fish until this is resolved.