Just because you have a male and female don't mean that they will get along. Nor breed for that matter. And if they do you have to have a plan on how to remove the fry from your tanks. It's very easy to flood your area with fry and no longer have a way to sell them off. Most places will at best give you a quarter per fry in store credit, if they buy them at all.
I took in 300 of Caspers fry and got a pleco out of it.
Plan for the worst, hope for the best.
Get the third tank, then you can try the breeding and have a safe place incase things don't work out.
Should be able to keep dithers with the Vieja and Parrot to get more activity from those tanks. Flowerhorns are not known for being nice so skip that one. The dithers will keep the Viejas tank going while otherwise busy with the FH. Swordtails or Molly's would be my choice.