POA holder acts on behalf of executors which in present case it was your father. POA holder olis bound to repay the received consideration to owner of property and she had not given the received consideration then she is liable to pay received consideration. Claim consideratio with interest. Neither you nor your father neither his property are/were liable to pay for illegal act of POA holder who had sold govt land in garb of POA while fact is that there was POA of your father in respect his own property and not in respect of govt land. POA had exceeded her authority and her act was illegal. 

So called second marriage is illegal. Let her file case and then you can have DNA test of her children. You and your mother in particular can challenge paternity of children. Mere mentioning in birth certificate does not have any value. 

POA ceases on death of principal 

2) however if any property was sold by POA then on demise of principal buyer can claim refund of money from estate of deceased principal and POA holder 

This property was sold in the year 2017 whereas your father died in the year 2023 only, hence he is very well aware of the sale of the property. therefore it cannot be said to be an illegal sale by the POA holder, moreover the power deed is executed by a registered document, hence the deed is also valid till the death of the executant.

The POA has acted on behalf of the principal hence the POA cannot be held liable for the fraudulent sale, because the buyer never raised this issue during the lifetime of the principal.

Let the buyer file the case and implead the legal heirs of the principal i.e., you and your mother, on receipt of summons, you can challenge the same on merits and documentary evidences. 

The legal heirs of your father's self acquired property shall include the children born to him out of his illicit affairs with his mistress as well.

To know about any other properties or fixed deposit amounts lying on your deceased father's name, you have to use your own source to find them out. 

For now you don't entertain any claim made orally by the buyer in this regard, you claim innocence about the deal as well as the properties sold to him, let him go top court and prove it against the legal heirs, it will take years for him to get his case disposed, in the meantime you can set things right by compromise or otherwise. 

Second lady does not have any legal status against your deceased father  but sons from your father have all rights of legal heirs. Death certificate  is public document, any one can obtain it. Her children can also claim legal heir certificate  from Court. It is very difficult to enforce any POA as the same is highly technical document. You can search through dharni portel to find out your father ’s properties.

Need to get a refund from POA by holding him liable for the same by filing suit

She only is liable to pay amount. Even if she is married, it is illegal. 

She has no legal claim. So no need to file any cases. and to recover the document and cash, file case in court. 

Check his wealth tax return.  

Dear Client,

The Power of Attorney (POA) holder is authorized to act on behalf of the executors, in this case, your father. The POA holder is obligated to return any consideration received to the property owner. If the consideration hasn't been returned, the POA holder is responsible for reimbursing it, along with interest. Neither you, your father, nor his property should be held accountable for the illegal actions of the POA holder, who wrongly sold government land under the pretense of the POA. It's important to note that the POA was meant for your father's own property, not for any government land.

The claimed second marriage is not legally valid. If she chooses to initiate legal proceedings, a DNA test can be conducted for her children. Both you and your mother have the right to contest the paternity of the children. It's essential to understand that mere inclusion in a birth certificate doesn't carry significant legal weight.