You stated:

"As uncomfortable as it is, you should comply with the investigation and be as cooperative as possible.

I STRONGLY disagree with this advise. A person should not cooperate with CPS, unless they actually have a Court Order stating that you must.

I wrote a post about it here:
https://steemit.com/familyprotection/@canadian-coconut/finding-a-lawyer-to-fight-cps-and-defend-your-rights

Most of the time, CPS doesn't have anything on you that is serious enough for a Judge to grant a Court Order. They want in your home, and to speak privately with your children, and try to get you to talk ... just as a Fishing Expedition. They are fishing for something that they can twist around and use against you to go back to the Judge and get a Court Order forcing you to be involved with them.

Once you let CPS into your home, you have waived all your rights. You have thrown your rights out the window. You are now at their mercy and your they can force you into meeting unreasonable demands that will damage your family emotionally and financially.
Never ever trust them.

You may be lucky and have a Social Worker who is only looking out for the children's best interests ... or you may luck out badly and get a Social Worker who has already determined beforehand that she will do everything in her power to make your life miserable and take your children.