can someone take demerit points for you

Ah, the old "can I hire a stunt double for my driving sins?" Unfortunately, no legal looph allows someone else to take your demerit points on your behalf. The Australian road laws are pretty clear: demerit points are tied directly to the offending driver's licence, not to any freeloaders willing to take the hit.

Trying to pass on your points might land you both in hot water, including potential fines or charges for false representation. So, unless you want to become the star of your own legal drama, best to keep your own record clean.