1. It depends on what power have you given to the said developer through your POA. The POA holder is empowered to execute exactly the jobs/works what have been mentioned in the POA executed by you. Please verify the POA minutely. If he has over acted, you can sue him,
2. You can be sued for any act which has been executed by forging your signature on documents. If you have authorised the Developer through the said POA to sale the developed flats pertaining to the developer's share to purchaser, then you are not responsible to its purchasers unless you have binded yourself with any or all the acts of the POA holders by entering such clause in the POA,
3. The Development Agreement is required to be seen for making any comment bin this regard. However, in normal course, the land lady is not responsible for any illegal act of the developer while making construction on her land.