You answered your own question where you wrote that "[you] let the cop in". No 4th amendment violation I see. Where police believe a crime in in progress or that harm would come, of course they will act.
You claim no assault occurred on your daughter--if accused, a judge will decide if an assault did in fact occur. Your claim that it did not will be your answer to the charge.
Someone reported you assaulted your mother--police must investigate that and you may have to answer to that charge.
What records were obtained, and why you think the records required your consent is unclear.
Why police had to come back four times is unstated.
An emergency removal hearing was in August and the children were removed 7 months later--seems like you had a lot of time to see an attorney to defend yourself and your children.
You are in definite need of legal assistance far beyond the ability of any online to help you. Recommend you contact a family law attorney immediately. Check with MI legal aid if you feel you might qualify for assistance.
NOT LEGAL ADVICE. FOR EDUCATION AND INFORMATION ONLY. Mr. Rafter is licensed to practice in the Commonwealth of Virginia and the US Federal Courts in Virginia. There is no implied or actual attorney-client relationship arising from this education exchange. You should speak with an attorney licensed in your state, to whom you have provided all the facts before you take steps that may impact your legal rights. Mr. Rafter is under no obligation to answer subsequent emails or phone calls related to this matter.
You are very subjective and self-righteous in your analysis of what appears from your description to be a proper action by CPS. They are interested in the child's welfare more than yours, as is the court. It sounds like you waived any 4th Amendment rights (presumably you mean freedom from unreasonable search & seizure) and further sounds like the search & seizure were justified. But, if you think not, see a Michigan family lawyer with experience in custodial battles with CPS.
I am not your lawyer and you are not my client. Free advice here is without recourse and any reliance thereupon is at your sole risk. This is done without compensation as a free public service. I am licensed in IL, MO, TX and I am a Reg. Pat. Atty. so advice in any other jurisdiction is strictly general advice and should be confirmed with an attorney licensed in that jurisdiction.
A question of illegal entry or search by officials is a complex one. It becomes more complex when there is reasonable cause for them to believe immediate action is needed to protect the health and safety of the child. It also becomes complex as to whether consent to entry is actual consent, or submission to assertion of authority. You need to hire the best lawyer you can find, familiar with local conditions in your area, if you are able.
Contact me at 248-399-6930 for a free consultation. You and I do not have an attorney-client relationship formed by our communications on this website. Advice given by me on this website is general advice based on partial information. You should not rely on any advice given without first hiring a lawyer in the area where the case is pending, and providing that lawyer with full information.
Ask yourself why CPS would try to intervene if it did not reasonably believe that there was something wrong. They are not trying to interfere in your life---they are just doing their job. Further, I believe it is clear even from your question that you consented to the entry of police in your home. And even if you did not, the CPS had an absolute right to do so for purposes of protecting the children.
My guess is that you face many personal and psychological issues that are not identified in your question, and that these issues are what have led to your current plight. You need to retain local criminal defense and family lawyers, but you also should work with our lawyers to put yourself in a program of psychiatric and psychological care.