1 fancy guppy
That is what my tank consists of.
This is what you have in the heated 10 gallon???
This is not the best stocking plan for a few reasons. First, the zebra danio (slider), needs to be kept in schools of 6 or more and needs at least a 20 gallon tank because they are active. Danios are also considered to be sub-tropical and the temperature the guppy and betta need would really be too high for the danio.
Second, a betta and a fancy guppy are probably not the best tank mates. Since bettas are territorial and sometimes aggressive, it is important to not put them with anything that resembles their own species. The long, flowing fins of the fancy guppy will just ask for trouble.
If I was you, knowing that you want a livebearer for a heated 10 gallon then I would probably stock 1 male guppy and 2 or 3 females to start. Then you could keep a couple of the babies, but then you would be making trips every month to the fish store to drop off the extra babies. Just seems like it would be a hassle after so long.