1) How could your father have sold land which was already mortgaged 

2) there must be clause in agreement that no third party rights can be created without mortgagee consent 

3) kindly clarify whether full sale consideration was received by your father ? 

if the land has already been sold to the government then no mortgage can be done by you. 

You can only sale the land for which you are having the title.

The sale deed for the said piece of land will not be considered valid in case your father received the consideration against the same earlier. 

Regards 

It would be better for you to take proper legal guidelines by showing complete files of your case to an advocate so that you can take a right path to handle your issues. Vague answers will not give you the exact relief .

Apply for legal heir certificate and on the basis of it , get rest 1 acre transferred in your name.

You need to file the objections for said incorrect entry of details and ask them to rectify. Else you need to move to civil court for directions or file a writ petition in the same at HC.

The information provided by you are insufficient to render a proper opinion to your problem.

However it can be understood that your father sold 3 acres of land to the government which was mortgaged. 

It is not understood that how a mortgaged property can be sold to any entity without NOC from the mortgagee?

Now you say that after redeeming the mortgage you have registered the 1 acre of land to whom?

Your questions are confusing hence you may better discuss with a local advocate who is practicing in the same filed about all such issues by producing the relevant documents and seek his advise on proceeding with all further issues on the subject.

1. As per the information mentioned in the present query, makes it clear that your father sold only 3 acres of land out of the survey number mentioned by you.
2. You need not to worry as when government involve then it is the duty of the official also to look for any incumbents in the property.
3. Now, as I can understand that the whole land was under mortgaged, but now you have release it and registered remaining one acre land.
4. On this point, it is also impossible to believe as how the officials let this happened when it was not free at that time.
5. This instance makes the sale deed not at all valid, and there’s are possibility that the same land was not even registered properly in the name of the government.
6. I would advice you to please inform the concerned department about the same as this may put you in the non needed litigation against the government one day for sure.