If you want all the siblings to be treated the same way, you would like each to have his/her own entry as a family, even if there is no family, or only a spouse. You may have lots of text and events for the individual and you would like to format them the same as the others.
Generally we don't care. UFT does present all the information we want in a reasonable form. However, for a book on the descendants of a particular couple, we want a chapter for each child that has a story (two died as children). To get the proper format, we added a non-existant child to a childless couple, and edit him out in WordPerfect. Not quite as tidy as we would like, but it does the job.
It's all a matter of personal perference. It would be nice to have an option for this choice, but it is far down my wish list. I need the citation problem fixed so I can use FJ reports in 3.0.