I have a similar problem My parents started calling me by my middle name as a child, so that is the format I have always used. Back in the day that was easy - school, driver's license, enlisted in the Air Force, passport, veteran's benefits, Global Entry, IRS, everything shows my middle name as my first name. For online access to those services both Login.gov and ID.me are set up that way. Because of that SSA doesn't recognize me when I attempt to sign in. To make it worse, before SSA started using those services I did have an online account with them. Now they will not send me any paper because I show in the system as having an online account. I've called Login.gov, ID.me, SSA and even went to the SSA office in person. They all said that there is nothing that can be done. I just enrolled in Medicare by phone - at least I think that was successful but I haven't received my card yet.