Yes, with good cause, this can be done. 

One example I recently experienced was the mother of the injured child was unable to open a bank account (something I learned after she was approved to be the GAL by the court), and I promptly petitioned the court to approve the aunt as the new GAL.  Luckily, this was all done promptly via written declarations, and mail, to the California Superior Court, and a new Minor's Compromise and Release in-person hearing was not needed.  The good thing is the court recognizes problems may occur with opening minor blocked accounts, and there is flexibility to help the minor child achieve this goal.