Unable to add spouse & children to J.C. Bell, Jr
As I could not find this ID in Family Tree, I assume the individual is in your "private space", as he is still alive.
From a general viewpoint there are a number of Help articles on the website, including https://www.familysearch.org/help/helpcenter/article/how-do-i-add-a-spouse-or-partner-in-family-tree and https://www.familysearch.org/help/helpcenter/article/how-do-i-add-a-child-to-family-tree.
However, if you already know how to do this in principle, but are just having a specific problem in adding a spouse and children to this individual, I believe you will only be able to get your question answered privately. A FamilySearch employee should be able to advise if you can contact Support (by phone or private message to an employee) and allow them to examine J C Bell's Family Tree page to see what might be causing the problem(s).