Good tip.  However, instead of spawning the magnet on the hair itself, I find it helpful to spawn the magnet on  the HAT instead, but leave the hat's magnet's dial value at 0.0, then, add the hair to the magnet's "objects to deform"  (thus the magnet & deformation zone are parented to the hat, but only deforming the hair).

This allows the hat to be subsequently re-posed on the head and yet, without readjusting the magnet, still scrunch any hair that happens to fall underneath at whatever jaunty angle I end up using.