False dowry allegations from ex-fiance

Recently my Brother In Law's Marriage got cancelled as the girl denied to marry stating our thinking doesn't match. Her family gave us 7lac Rs to prepare jewelry of the bride. We asked them to take back all the jewelry with bill as the marriage got cancelled and asked to settle engagement expenses 50-50. They denied to take the jewelry back and asked to returned cash, which we did bearing loss from returning the jewelry. My brother in law booked he to-from flight tickets for the honeymoon to Denmark, which was non-refundable. again we had to bear the loss. My B-I-L transferred cash to girls account occasionally for gifts which they first denied and later agreed when we presented bank statement. Now when it comes to settling engagement expenses, they are asking to drop their stuffs with some relative. throughout the period they have been threatening us to file legal case and dowry case. At the end its us who is in loss both monetarily & emotionally. We got to know that she had one more marriage cancelled for such reasons in past. Could you suggest how do we report this so that this doesn't happen to someone else in future.