family law in Wisconsin

If a woman is legally married in the state of Wisconsin, but has been separated for over 11 months and living with another man in the state of Michigan and has gotten pregnant by the live-in man, can she legally put the true biological father's name on the birth certificate even though it is not her legal husband's child and she is still married to him?

you should always put the biological fathers name on the birthcertificate. Even though you are not married to him. If you two ever split up and you wanted to get child support, the child support agency would have to know who the real father is to get the support from him. And I don't really think your husband, or ex-husband if you get divorced, would like to be paying support for a child that is not his.

In Illinois - I had a baby girl, was married, but not to her father. When she was born, the hospital gave me some forms to have husband sign to say that he was not the father. Once the forms were signed, they put the 'real' father's name on the birth certificate. If I didn't get the papers signed, my husband would have been listed as her father on the birth certificate.

Not sure, but I think this is true in most(all) states.