I would like to add a last name, not change a name. Let's say, my last name is Smith and I want to make it Connor-Smith. What do I need to do to add this name? I would like to do this because my son has his father's last name (Connor) and mine (Smith) as shown above. So, I want to have the same last name as my son. I wasn't born in NY, but in MA. However, I am a resident of NY. I read somewhere that you can just start using the new name and do not need to go to court, is this true? Will I need to go through the same procedures as a name change?
If Connor is a legal name of yours due to marriage, since Smith is already your name, you can simply start using both, and prove through your marriage to social security, DMV, etc, that you are legally entitled to use that name. When people marry, there is no legal proceeding necessary for the wife to adopt the husband's name, or vice versa.
A court proceeding to change your name is necessary when / if you are not already legally entitled to use the name.