Nice Drew!
A system consisting of 4 stars with such spectacular differences in spectral types must be very unusual. Are there any known real systems with that setup or similar? Or did you infact want to make Prism stand out a little extra?
Not as unusual as you might expect. The two bright stars are pretty close in size and configuration, I've just played with the mass of one to make it more 'blue' (hotter).
The other two (including Prism) are also quite close, Red and Orange respectively. These configurations are pretty common and Red Dwarfs themselves are as common as muck!
Is there a direct analogue in a 'real' star? No, there's not but I've based it on extrapolation from real star systems such as Albireo (double yellow and blue pair - google it, very pretty) and even more complex sextuple systems like Mizar or Capella. Somewhere out there there is a real version of this system... perhaps not far away.
Our system is actually pretty unusual in that we only have the single star.
As for planets - are they believable? Yes, we've confirmed exoplanets around stars in quadruple star systems already.
I've put the Prism system about 150 light years from Sol (until star map confirmed). Right now it's in the constellation of Leo (I was born in August) and would be, if it were real, magnitude +14, which means you would need a pretty decent amateur telescope to see it and a professional one (20" inch diameter or better) to actually see the individual stars in the system.
Cheers,
Drew.
ps. But yes, I wanted the Prism system to stand out, but be realistic in construction.