Since she is your Aunt and not directly related to your family its rather difficult to get extended her visa but you can request for 14 more days for that you have to produce Booked ticket copy which appears to be that she is travelling on so and so date on that basis they may give further extention of two weeks maximum...but while her stay in u can not obtain another visit visa for that she has to exit the country if you can able to obtain a tourist visa by Hotel but its difficult either. Coz during her exit and re entry if she didn't get new visit visa immigration law does not allow her to get into the country... I suggest that do not take that risk...regards,

Naeem