Hi all, I know there is a function to create a midplane very quickly.

Is there any command to create two mirrored planes from a midplane?

Lookind at the screen-shot below, I would like to create two mirrored planes at set distance starting from 'Right Plane' so that if I need to change the distance between the two planes they stay symmetrical with respect to the right plane?

I've done it by setting a formula. Is this the only way or I'm missing some other easy way?