"We need to search your home."

"That's not going to happen. If you give me your information I will have my lawyer contact you. But right now I would like for you to leave my property. I'm going to shut this door & if you attempt to force your way in I will protect myself & my family & my home with deadly force." - close door. Call local sheriff & tell them you believe someone is pretending to be from the govt in order to abduct your children.