My daughter marriage take place under 420

My daughter married to my son in law on the ground of information provided by my son in law on matrimony site. All the information provided by my son in law and his family was false and fabricated written ( e-mailed) information regarding his house, salary ,qualification and health. We have proofs of his email copies.After the marriage my son in law and his family asked for money and forced my daughter to take personal loan and transferred to my son in law account,purchased items with the help of credit card of my daughter and sold it for cash to others, purchased car on EMI taking loan from bank on daughter name,bounced cheques for payment of flat booking on my daughter.s name, taking loan from my daughter.s friend etc by my son in law. My daughter filled case in CWA and as per CWA recommendation FIR filed against my son in law and his family but police didn't filled any case under section 420. The FIR filled under section 498a, 34 and 406 only , We made several request to police to file 420 case against my son in law as to get married to my daughter ,he has provided fraud & fabricated information about his salary ,house, social status, education, health & hiding facts of his past. Kindly advice how to file 420 case against my son in law.