Quote - Do you know which way I can change magnet pp2 to parent it to selected body part?

No way I know of to automatically have it change to the selected body part. Unfortunately "actor $CURRENT" will not work in the smartparent line.

You can use a pose file to change the 'smartparent' line. But I'm not sure that is any easier than just going into the Object menu and using "Change Parent".

{

version
    {
    number 3
    }

baseProp Mag Base 1
    {
    smartparent head
    }
sphereZoneProp Mag Zone 1
    {
    smartparent head
    }
}

The snag with using a pz2 is that the number of the magnet in the pz2 must match the number of the magnet in the scene, including any "_".

If you are just interested in having symetrical magnets on diffrent sides of the figure, you can use ERC to have one magnet mirror another magnet. See my freebie "MirrorMags32" at sharecg for an example, and ockham has a py script that will create a copy of a magnet on the opposite side of a figure.