You won't get into trouble if your husband is not served, but the legal proceeding will not go forward until he is served.  You could request a continuance (postponement of the legal proceeding) and then your husband could be served after he is out of rehabilitation.Although you said your husband can't be served while in rehabilitation, a process server might be able to leave the documents with the treatment facility and then mail copies to your husband which is substituted service.  If that isn't possible, then requesting a continuance would be your best option.