More details would be nice, but in gengeral, if you are granted Power of Attorney, your job is to act on the wishes of the person who granted you the privilege. If that person is incapacitated, you act in their best interests.
Also, remember that POA expires at the death of the person who granted it.
As Babalou says, the duty of someone who has been given a POA is to the person who gave it to her. Not to other family members. That being said, I would think life would go more smoothly if the person with POA at least listened carefully to what other family members have to say, even if in the end the POA-holder doesn't do as they suggest. What do you have to lose? Sometimes two (or more) heads are better than one.
No the POA does not respond to others' wishes. Get a blank POA and read it, it only empowers the POA to carry out the wishes of the person while they are still alive. The POA is expected to maintain complete confidentiality, meaning no disclosure to the curious.
Also, remember that POA expires at the death of the person who granted it.