I understand your concerns about the perceived harassment by the process server who is trying to personally serve your brother-in-law with a summons and a complaint regarding a civil action.Unfortunately for you and your mother-in-law, registered process servers by statute are allowed to go onto land where the person who is to be served with the summons and complaint is believed to be located in attempts to effect service.Attempts to serve albeit repeatedly can be seen as harassing but are not. However, harsh language from the process server during the attempts is another matter.From what you have written, it does not appear that you have a factual or legal basis for suing the process server and the plaintiff corporation for harassment.