How do you set up your bridge in order to avoid individual strings going down in pitch when you bend a lower string (example: bend the G string on the 15th fret whilst hitting the B string (at the 12th fret) at the same time?

ive been playing my standard for ten years and ive never once had any string go down in pitch because i bent another string...
Put as many springs in the back of the guitar as you can and then tighten the screws as well. Unless you still want to be able to use the whammy bar, in which case good luck.
R.I.P. My Signature. Lost to us in the great Signature Massacre of 2014.

Quote by Master Foo
“A man who mistakes secrets for knowledge is like a man who, seeking light, hugs a candle so closely that he smothers it and burns his hand.”

Tighten the springs in the back maybe? Like Onthe Skids said i dont know why you are having this problem. I have a cheap squier and this doesnt happen to me. It sounds like your bridge may be coming up in which that means you should tighten the springs.
I think the problem may be accentuated due to the fact that I use a heavier string gauge. Theoretically, bending heavier strings should pull the bridge more.

What is everyone's experience with 9s? Would bending cause the bridge to move?