When our divorce started my stbx was self-employed. We couldn't figure out for sure how much he made. (It's taken so long he's gotten a job that we can track...problem solved.) Anyway, you may not be able to get to his exact income, but my attorney explained to me (if I understood it all right) that there are 'referees' whose job it is is to figure out how much someone makes. I could use things like bank records of money he had transferred into our joint account, deposits made into any of his accounts, etc. He had to explain where that money came from. If, however, this is brought before the courts, will there be consequences to you for past taxes if the income was not claimed?
Good luck with your venture. What kind of person expects his child to keep a secret like that? Horrible!
It just depends on how much you are willing to spend to get what you deserve.
An attorney can get a court order that orders all banks to release his financial documents and those financial documents can be then sent to a forensic accountant. The forensic account will be able to determine #1 if they have all of the bank accounts (because people transfer back and forth at some point between an unknown account and a known accout) and #2 how much income there really was.
During my divorce my ex swore I had hidden millions, ya right, I work for a living. I had to hire a forensic account to prove exactly that, I had no hidden money. They tracked everything for three years, and I mean everything. It cost almost 10,000 dollars but considering the 1/2 of the million I was going to have to pay it was well worth it. It also helped to prove I could not afford to continue to pay him spousal support. Worth it to me. I made payments to this account for two years before I got him paid off.
We also used the same type of service to prove my ex was lying about his income, he was claiming unemployment, workmans compensation and retirement benifits all at the same time. He not only had to have all of this income considered he also had to take out a 2nd on the house to pay back what he was not intitled to. Once again, worth it to me.
Good luck