If my mother has joint custody for her 15yr old daighter can she give a power of attorney or legal guardinship to me without his consent

Question

If my mother has joint custody for her 15yr old daighter can she give a power of attorney or legal guardinship to me without his consent

Answer

Only a court can grant a guardianship. To obtain a guardianship of a child would require the consent of the parents.

I can't answer the power of attorney question without seeing the proposed document or knowing the proposed powers.