Hello and thank you for your question.
Only a fully briefed lawyer will be able to give you firm advice as to your prospects of including assets that have been shifted to your parents in law's name, however, a few things you should know that may give you comfort:
If the family court believes money has been siphoned to relatives simply for the purpose of defeating a spouses claim the court has the power to claw back such funds:
http://www.austlii.edu.au/cgi-bin/sinodisp/au/legis/cth/consol_act/fla1975114/s106b.html and the following link will refer you to a list of cases where this legal provision has been invoked, so you may find a case which reflects your situation:
Accordingly, provided you act promptly, and the court is satisfied such transactions were not bonafide and for legitimate purposes, your ex will likely not succeed in such measures.
Even if such funds are difficult to recover for some reason, a court may still make orders on the basis that such assets formed part of the pool for division and then make sure that your share is received at of any other assets your ex may hold, such as his superannuation, or other personal property.
I would strongly recommend you engage a lawyer to assist you. Given the conduct of your ex and his family in trying to thwart you, your situation does not sound like one which should be handled without the invovlement of a family lawyer. Once you are legally represented, they may be far more reluctant to play such games with you and hopefully a sensible settlement can then be reached without the need to refer the matter to the court.
If you don't have the up front money to pay for a lawyer, be aware that provided it appears you are likely to recover a significant sum, you should be able to find a family lawyer willing to work on the basis that his/her fees will be paid at the conclusion of proceedings once a settlement is reached or a judgment made by the court.
I trust the above assists.
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