Reasons to use a professional service.
Often there is nothing to prohibit a family from using a “non-professional” relative, friend, or acquaintance. Many court orders will allow that as an option, providing both parents can agree on whom to use. That often does not work out for the following reasons:

First, there is the difficulty in finding someone on whom both parties agree. Chances are very slim they will be able to find an individual everyone will trust and feel comfortable with.

Secondly, it can put a strain on friendships. Many well-meaning friends and relatives will agree to provide the service but will quickly tire of the regular commitment and/or being in the middle of others conflicts. It is difficult for friends and relatives to restrain from taking sides.

And, finally, it may actually detract from the quality of the parent/child time together. It is often tempting to spend time interacting with the acquaintance rather than focusing on the child. 

What are you being asked to do?
You have been asked to do a very important job - to supervise visits between a parent and a child. You have been asked because supervised visitation has been ordered by the court, and because the parents feel they can trust you in ensuring the health, safety and welfare of their child. In accepting this responsibility, it is clear that you care about the children and family involved, and are willing to perform the tasks of a non-professional provider. 

So are you the person for the job?
Supervising visitations is a very important responsibility that can be difficult at times. If you don’t think you can put your personal feelings aside, don’t have the time to supervise properly, or for whatever reason you feel uncomfortable, then you shouldn’t agree to do this.