1. The property is HUF property, but none of you three sisters qualifies to be a coparcenor. You have not mentioned as to on what basis do you claim coparcenory rights.
2. You are governed by Hindu law, so you can sell your share in the undivided property of your deceased father only if your share has been demarcated. Absence of partition does not impair your right to execute a sale deed in favour of the buyer. You may have a fixed share in the property, but is it capable of identification? Which part of the property would you sell? Was a family settlement executed during the lifetime of your father or thereafter whereby and whereunder you and your 3 siblings agreed to possess a clearly delineated portion in the property? Since the property is undivided you have to first offer your respective shares to your brother. He has the right of pre-emption.
3. The alienee, when he goes to court for entering into possession of the property after effecting division, will be disentitled to seek a specific portion in the property commensurate to his share. The court will decide which portion is to be allotted to him. If the property is incapable of being divided by metes and bounds the prospective seller may back out,
4. The concept of alienation of joint family property on account of necessity or benefit of estate is not attracted to your case. Hence, you cannot alienate on this ground. Alienation of joint family property due to legal necessity or for the benefit of estate does not allow a coparcenor to pocket the sale consideration.