If you are using a private process server, the process server should continue until the father is served.  The process server might do a stake-out if necessary to serve the father. If you are using the marshal to serve the father, the marshal might only make a limited number of attempts.The father will need to be served.  If he is not served and doesn't show up in court, the case won't proceed until he is served because until he is served, he hasn't received notice.