You didn't answer the question.
We can't answer the questions without it, really.
The IRS generally doesn't going to look through people's bank accounts.
The recipients of such things (which I have no idea whether it was just division of marital property under a qualified order or an ad hoc distribution which be a gift) don't generally owe any taxes on it. You however may be obligated to file gift tax and this may apply towards your lifetime exclusion.