I have a friend. Let's call him John Smith. John Smith has a son. I'll call him Robert Smith. John, their family and Robert's friends all call the child Robert or Robby. No one calls him Rob.
Now, in his free time John writes novels. He wants to publish them under a pseudonym, and the perfect pseudonym he came up with for his writer self is Rob James Ford. (I'm still making up all the names, but the principle of similarity is the same.)
John Smith is a bit worried how his son will feel when he grows up and discovers that his father has "appropriated" his own name.
Little Robert is eight years old today and knows quite a few other Roberts, among them one of his best friends, so he is used to the fact that his name is not exclusive to him. But he also knows his father by the name John and that Rob is one possible short form of Robert. When he reaches adolescence and has to find his adult identity -- possibly accompanied by conflicts with his father -- he might feel that his father has been transgressing into what is rightfully his own by using his name for himself. It might feel wrong to Rob Smith that his father calls himself Rob Ford.
What do you think?
Is it unproblematic for John to call himself Rob? After all he does not call himself Rob Smith but uses a different last name with a version of his son's first name, so there is no mistaking Rob James Ford for Rob(ert) Smith. But at the same time Rob is the name of John's son, and they both recognize this.
What should John do?
John found his pseudonym through a painstaking process and has been unable to come up with another pseudonym that feels just as right to him. Giving up Rob as part of his pseudonym would be a pity.