1. She may be prosecuted for perjury by her second husband.

2. It is the prerogative of the court to sentence a person to jail or let him off with fine. However, in perjury cases the practice is to sentence the accused to imprisonment. It is very rare that the court lets go a person with fine only in perjury proceedings.

3.The second husband has a good case to seek the annulment of the marriage.

4. She and her brother can also be prosecuted for cheating. All those who were aware of the first marriage of this lady but concealed it can be prosecuted and punished for cheating.

The Indian Penal Code (IPC) under Section 191 defines perjury as giving false evidence and by interpretation it includes the statements retracted later as the person is presumed to have given a false statement earlier or later, when the statement is retracted. Under section 191 of IPC, an affidavit is evidence and a person swearing to a false affidavit is guilty of perjury punishable under Section 193 IPC which prescribes the period of punishment as seven years imprisonment. However, action against making a false statement should be initiated during the trial itself, and not at the end of it which may take a long time. That may be a deterrent against persons who intentionally mislead the court or make false statements under oath or file tainted affidavits much against the public good. This is one of the reasons initiating action against a person for perjury after the trial is over why in India several perjury cases go totally unnoticed as a fresh trial begins on perjury running into years.

Further she can be charged of cheating under Section 420 of IPC

Dear Querist

My opinion on your queries are as under:

1) Can a perjury case filed against wife who had signed false affidavit in the court that she is unmarried ?

Opinion: It may be filed.

#2) Also will she get imprisonment under sec 193 or just a fine amount ?

Opinion: Its depend on the court, the court may punished by imprisonment or by fine only.

#3) Is this a perfect ground for marriage annulment for second husband ?

Opinion: No, this is not a perfect ground to get annulment.

#4) Can a cheating case(IPC 415, punishable under sec 420) filed against second wife & her close relatives ( e.g. brother,sister,mother,father,uncle) as all of them were involved & hidden the information ?

Opinion: No, it can not.

#5) What are the chances of imprisonment under sec 420 to all those involved if applicable or would it be fine amount only?

Read section 420 of IPC

420. Cheating and dishonestly inducing delivery of property.—Whoever cheats and thereby dishonestly induces the person de­ceived to deliver any property to any person, or to make, alter or destroy the whole or any part of a valuable security, or anything which is signed or sealed, and which is capable of being converted into a valuable security, shall be punished with imprisonment of either description for a term which may extend to seven years, and shall also be liable to fine.