Some jurisdictions require state (or county) agency involvement at least to a certain degree. For example, in the State of Washington, most (if not all) counties require pre- and post- placement reports. That may very well be the case in Michigan. I highly recommend discussing this with a local attorney in Michigan knowledgeable about adoptions as they can sometime become rather complex legal proceedings.
This comment is made as general information and is in no way to be considered legal advice. Attorney's making such comments have no information beyond the information provided in the question presented. Additional information is necessary before an attorney can give specific advice. Please seek legal counsel.
This is a complicated process and I suggest that you retain an attorney to assist. However, with that said, the adoption process of a relative child is different than that of adopting a child you have no relation to. This involves filing different pleadings with the court, home inspections and court hearings.
My number one suggestion to you is to file all the appropriate paperwork as soon as the child is born. I had a case where the client didn't file paperwork and then just shy of two years later the biological mother asked for the child back and was granted that request. You should absolutely have an attorney with experience in this matter.
I wish you the best of luck.
***Answering legal questions is a complex matter and cannot be done without further research. My answer here is based solely on the information given in the question and should be taken as informational only. This is not legal advice. My answer here does not indicate that I represent you now, or that I will represent you at a later time. I take clients on a case-by-case basis, and only after initial consultations. ***
Sign up to receive a 3-part series of useful information and advice about child custody law.