What to do with my 10 and 20 gallon aquariums?

If you weren't trying to breed them then I would say that your stocking arrangements are fine. If any of them breed then your tank will be overstocked. If you put more fish in with the danios then your 10 gallon would be overstocked. I would get a breeder tank to breed the swordtails in because your going to need a tank to grow the fry out in anyway. If you keep them in your regular tank they could get eaten, sucked into the filter, and it will be hard to feed them fry food.