Let us first see what a family law paralegal does as part of his/her profession.

A family law paralegal assists her employer in delivering family law services to clients. Effective paralegals working in this area of law will know something about custody, divorce, tax & finance law, adoption, and even the social services available in the area. Because many matrimonial matters end up in court, a working knowledge of litigation and family court rules is essential. These paralegals will need to anything from filing motions or pleadings and preparing discovery to searching financial or tax records and arranging mediation. The para-professional here will likely be the liaison person between the client and the attorney; someone able to handle not just the legal side, but also the human, emotional aspect of this type of practice.

source: http://www.raritanval.edu/departments/busadmin/full-time/Defilippis/tops/FamilyLaw.htm

While lawyers assume ultimate responsibility for legal work, they often delegate many of their tasks to paralegals. In fact, paralegals?also called legal assistants?are continuing to assume a growing range of tasks in the Nation's legal offices and perform many of the same tasks as lawyers. Nevertheless, they are still explicitly prohibited from carrying out duties that are considered to be the practice of law, such as setting legal fees, giving legal advice, and presenting cases in court.

source: http://www.bls.gov/oco/ocos114.htm

Thus, we can say that it is ethical for Harold to help his friend in preparing the papers for divorce. However, Harold is not qualified in terms of presenting cases in court. But, he can be of great help to his friend isabel, not only in terms of providing assistance in matters related to the filings for divorce and working with the attorneys, but also from emotional and human point of view as Harold is experienced in this field and can help Isabel to face this situation with utmost mental strength. Thus, basically Harold can help her by coordinating with Isabel's attorney and carrying out all the tasks as required by the attorney.