alternative of power of attorney POA from mother to son

We are two brothers and three sisters and all are married. After my father's demise we got a plot originally booked by my father which is now on our mother's name, and built that with three stories. Mother has written a will for specific portion. My younger brother has two upper stories and I have only ground floor according to that will. I want to give my portion on rent which has become commercial in due course. Mother some how is relectent to gove a power of attorney on some family member advise. Are there any other alternatives apart from GPA for me to go ahead with my agreements?