In the "you knew there'd be drinking" involved in this story category I'd hate to see his kids get punished for his blazing stupidity but this is certainly taking advantage of the situation. Conveniently, they're "minor" kids so his girlfriend/daughter will, presumably, actually be the trustee?
I was gonna start a thread about this, but the title would have been "48 Year Old Man dates Adopted Daughter!" with the punchline being that she's 42.
If he did legally adopt her, wouldn't it be illegal for his to continue a sexual relationship with her, even though she's a 42 year old adult? I'm just curious. I don't know how the incest laws work when you're not actually related by blood.
The plus side is that when, not if, this winner goes to jail, she doesn't even have to bother with a divorce to abandon him and take all his money. Remember, folks, she's taking all the money and never seeing him again (say it with me) for the children! (read for herself because that's legally what she is.)
He would be his own uncle (if it was a boy; you can make the appropriate adaptations for a girl). Being the son of his mother's father, that would make him his mother's brother. Imagine two kids born to the same couple. They never would be able to figure out who was who...