I believe an up to date NEC code book and a BICSI manual could be handy here.

I'm not going to go look it up

Yet, at some point, and/or due to design

The ceiling support wires where not supposed to be used for ANYTHING except for supporting the ceiling grid.

If/when you add your own support wires, they must be attached to the grid.

There are points of attachment meant to support the grid only

I believe the reason you attach yours, is so that it's not swinging around up there and designates it as a "wire" support.