It is just a domestic enquiry. But, why you are worried about the appearance of a professional lawyer? Domestic enquiry is a legal process before issuing you a charge sheet. After the domestic enquiry, you will be served the charge sheet of the allegations against you, negate them with your full force. Your natural justice is not violated by participation of a professional panel lawyer, as per my view. For the sake of objection, you are free to raise the issue of participation of the professional panel lawyer, if you wish.