Water parameters shouldn't matter too much. You need to get a pair first. I doubt that accusation of 2 males and 1 female is correct, because Discus are near impossible to sex, unless you see them breeding.
Softer, more acidic water will help, but shouldn't matter too much, as long as the water isn't too hard and too alkaline. What do you have at the moment?
You will need more Discus then that, if you are really keen on getting a pair. Place 5+ in a tank, and then wait for a pair to form.
What size is the tank?
What are you using for filtration? Is it bare-bottom tank floor? What do you have in the tank for them to breed on? Any tank mates other then the Discus?
Discus need very clean water, and the fry need the same plus some.
Are you letting the Discus raise the fry, or are you doing it artificially? What size tank(s) do you have for the fry to grow out in?