Make sure you document everything for awhile.

Simple things like, you fed them these meals today, you helped them with homework today, you read them a bedtime story, you played with them, you took them to a playground, you cleaned the house, you did the dishes, you x y and z.

They will be like the police, in the regard that they will try to lie to get you to "slip up" or accidentally say something they could take as "incriminating". I know someone who works in this field who is a really good person and doesn't lie to get things done.

But the overall thing they look for is stable home, running water, food, clean house, no bruises, children seem happy, safe environment, paychecks/money coming in to feed/cloth them, clothing, clean kids.

And like I said, just document everything for awhile. Not only does it show proof, but on another level it proves that you are very serious about the childrens needs by documenting everything. I hope all goes well for you, it can really suck to be at the mercy of a liar/sociopath CPS worker.