I have a relationship with a guy that was before married and has two kids with his ex she makes threats to him that she is gonna open the child support if he doesn't give her 1000 dollars per month for two kids? How can he open the child support?

He can go into the child support and open a case himself they will look at his income and they make the decision on how much.

They pretty much take 25% of what you gross.

1000 a month is alot he should not allow her to make threats against him and he should open a child support case himself they will most likely take around 700 since a child is around 367 regardless of what he does for work, if he cant pay the full amount they will just take what they can 100 here maybe 200 there it will still be less than 1000 though. Goodluck