Order 2 rule 2

1.    Yes it is very much applicable in Family Court matters.

2.    See, the object of O2/R2 of the Code is two-fold. First is to ensure that no defendant is sued and vexed twice in regard to the same cause of action. Second is to prevent a plaintiff from splitting of claims and remedies based on the same cause of action. The effect of O2/R2 of the Code is to bar a plaintiff who had earlier claimed certain remedies in regard to a cause of action, from filing a second suit in regard to other reliefs based on the same cause of action. It does not however bar a second suit based on a different and distinct cause of action.

3.    I suggest sit with your advocate and understand two important ruling of Hon'ble SC in reference to context to get further clarity
Ref.:  Gurbux Singh v. Bhoora Lal [AIR 1964 SC 1810] and
Ref.: Alka Gupta Vs. Narender Kumar Gupta [(2010) 10 SCC 141 = 2010 AIR (SCW) 7037]

4.    Ideally she should have filed S. 27 HMA which could have been filed after the said divorce decree (which you say she got or) has been obtained which is the case in hand. But then litigants do get carry away by controversial advises of advocate(s) and this is one such case which is my opinion hence you are referred to above Judgments which if applied correctly by your side it will bar her further advances but remember her suit cannot be dismissed without trial merely because the court feels dissatisfied with the conduct of the plaintiff the moment above Judgments correctly plead by your side.

Let me make it clear little bit,  

In the divorce petetion, they mentioned it like at the time of marriage certain amount of money, gold and other valuables were given as parental share and those were not returned to them. But at the end of petetion, they plead only for divorce and there is no demand for money or gold. 

When family court allowed divorce the judjement also clearly said that court did not considered monetary aspects as they petitioner is not plead for it. Now they filed a second suit demanding the settlement of monetary part. In second petion, they mentioned that they did not plead for the money and assets in divorce petition and the reason they mentioned is their advocate that time omitted it without their consent.

A statement is there in second petition that they purposelfully omitted the money part)

So is it correct to understand as follows:

A divorce petition in family court shall include the plea for divorce and settling of the properties at a time and no seperate suits are allowed under O2 R2.