So many tanks, so little time. Since you can't get more time you might as well get more tanks.
If you want to spawn fish, it is almost always best to do so in species tanks and to be prepared to remove and raise eggs/wigglers/fry in some cases.
All fish pretty much see eggs or fry as food. Expecially when they belong to other fish. But also even their own in many cases, especially for the egg scatterers.
Standby- As for swordtails all being a snap to spawn. If you can find them, let me know how you make out with X. montezumae, Rascon strain. Heck, even my blue/greens montys would stop for months on end. The mottled ivory are pretty easy. But all three are also voracious fry eaters.