I would speak to a solicitor for this type of advice. In order for you to be given her EPOA (in NSW) she must have the mental capacity to do so, a solicitor meeds to give a very specific certificate stating that she is of sound mind at the time of execution. If there is any doubt about her mental capacity she must sit an acquity test with her GP and must receive a specific score.

This is for an enduring POA. A general POA does not have the same requirements but no solicitor worth his salt would prepare one and have it signed if there was no mental capacity and the use of your POA could be challenged.

As far as her not having capacity and you becoming her EPOA you will meed to go through the Guardianship Tribunal and from what I have seen it is not an easy process.

Good luck with it all and like I said first off you need to see a solicitor and get the appropriate advice for your relevant state.