[Space] Making a solar system with 3 (semi-) habitable planets?

[kdtipa]

The reason it's only one planet in a system that supports life is that in reality there seems to be a sweet spot in the orbital ranges that's just far enough not to be "too hot", just close enough not to be "too cold"... it's just right. And the distance planets have to be from each other in order to not drastically affect each others' orbits has to be pretty high too... I could be mistaken, but I think in reality it's impossible to have two planets in the sweet spot range... almost.

I also read some hypothesis about the possibility of a sister planet to Earth in exactly the opposite point of the orbit. It would be on the opposite side of the sun always. Of course it was shown that our own solar system has no such planetary body, but in terms of physics, it is possible.

There is one other thing to consider: Lagrange Points

You could possibly say that the biggest planet of the three that supports life is the "Earth", and that the L4 and L5 Lagrange Points have "planets" capable of supporting life. They'd all be at roughly the same orbital distance. The only thing you'd be fudging would be the mass of the other two planets.