First, what size is your tank?
Dwarf puffers are a big no-no, enless your going to be using your other fish as feeders, if you know what I mean LoL.
If you have enough room (when you tell us what size tank you have) then I would suggest getting atleast 3 more danios because if kept in smaller groups they tend to be more nippy-and that could be bad news for your female guppy and your lone neon.
Neons also like to be kept in groups of 6 or more, so I would add more of those.
EDIT: Oops

) Didn't see your signature.
I would suggest finding the danios a new home, because they are very active fish and would love a tank of atleast 20 gallons to live in. A 10 gallon doesn't really give them the room they need.
After that, you could add 5 more neons, and then get your female guppy a guppy friend. I would suggest another female friend instead of a male because the male might harrass her too much. Hope that helps
