abandonment and power of attorney

I have been forced to put my ex on supervised visits with our son. He has not taken advantage of the visits in over a year. I live in CA and I can see there have been several who've addressed this subject here, but I want to be clear that surrendering his parental rights can/cannot be allowed in this state. I've also decided to give my parents power of attorney of my son in the event I am incapacitated or die. How much power does that give them, worst case senario, if my ex tried to fight them? Will Power of Attorney hold water in court? Please advise. I want my son protected. I am not a vindictive ex-wife. I would not refuse him visitation. I have declined child support from him because I dont want that over my head and for once Id like the satisfaction of being completely independent. Im getting there. But also, Ive been on his side of the fence with him. He has child support payments to his ex-wife and his sister. (Long story) I dont want to be part of his burden.