Is it a sin for a guy to change his last name because he had bad problems with a side of the family? or to swap his middle and first name because he goes by his middle name and it would make things easier?
The only way it would be a sin would be if the reason was to avoid being punished for a crime.
If you are commonly known by a particular name, then there is no harm in changing it. I have also known people who changed the spelling and/or pronounciation of their names in order to avoid embarrassing/offensive letter combinations or sound combinations. (For example I have a friend who changed his last name to “Falk” who had more of a short “u” sound in the middle of his name before. He is Vietnamese.)
Is there something that leads you to believe it could be sinful?
No not really I was just wondering
Now if one deliberately changes one’s name for no reason other than to spite one’s family then that might be sinful. But it wouldn’t be the name change itself that was sinful but rather the spite part.
The mere fact that family members might not like a name change or that a person is trying to distance himself from others of that name is not sinful.
As long as you are not changing your name for the sole purpose of spite, or for deceptive or fraudulent purposes, there is nothing wrong with it. More than one person in the Bible changed their name, you know! Saul became Paul, Abram became Abraham, and so on.