Hey @Account Closed
I run a small PM business in Milwaukee and I think you are over thinking this a bit. There should be no issue with or your husband filing the eviction for your father in law. You can always have an attorney do it for you. Charge for that including filing fee should be about $3-400. That will take all the headache and emotion out of going to court. Send the 5 day notice via certified mail so the tenant can't play the game that they didn't receive it. You will have to fill out an affidavit of non military service and affidavit of service then you are set to file or have your attorney file. Court date will happen in 1-2 weeks then you get the writ of restitution. If they don't leave by the time the court says then you will have to hire the sheriff. I do on average of one eviction a month and have never hired the sheriff. If you don't think they will leave on there own, tell them you will put a judgement on them for all rent and damages then garnish there wages. This is usually a good enough empty threat to get people out.
Good luck and hope your father in law gets better.