1. Assuming that your parents died intestate (without executing a WILL), then the share in the property devolves equally to all the children (sons and daughters). In the instant case, the entitlement to the share in the property devolves equally to 2 brothers and 2 sisters, i.e., 1/4th or 25% share to each one of them in all the movable and immovable properties of your deceased parents.
2. Transfer of property by you in your name, by obtaining affidavit from other legal heirs is not the valid legal route. The correct way to get transfer of property in your sole name is to get the registered Release Deed from your brother and two sisters, relinquishing their individual share in the property in your favour, by paying adequate stamp duty and get it registered in the jurisdictional Sub Registrar's Office.
3. Your 2 sisters and power holder had only submitted an affidavit but they had not executed a registered Release Deed relinquishing their individual entitled share in your favour and hence they have withdrawn their consent previously granted to you.
4. Your power holder can only give consent on your behalf only for the clauses mentioned and agreed by you through POA.
5. You are legally entitled to obtain a copy of objection as against you only the objection has been lodged. Demand for a copy of objection from your siblings and builder.
6. Send a legal notice to your power holder for not providing you a copy of objection. You can claim demurrage from the power holder if you can provide evidence for the damage incurred by you on account of the action by your power holder.