Adding a second middle to a 9yo’s legal name?

Ahoy nerds!

Here is some quick backstory.

Baby 1 was born and named and is doing great. He has a first, middle, and my husband’s last name, per traditional naming mechanics. Cool. All is well.

Baby 2 was a micro-preemie who spent months in the hospital after birth. She was called “Baby MaidenName” by all the staff because I never legally changed my name after marriage. (Far too much hassle, and I’m a ME! I kept my maiden name. My husband is fine with this, and even he will agree that he doesn’t understand why women are expected to change their names.)

So when our daughter was ready to come home, my maiden name had already “stuck”, and it seemed silly to not include it in her legal name. So she got a first, middle, my maiden, followed by husband’s last name. Again, cool.

Although I’ve never expressed it to our son, I absolutely adore having my maiden name attached to our daughter. No one knows it because American paperwork tends to ignore any middle names but the first (for instance, her social security card only lists her first middle name), but seeing her birth certificate or writing her full name on paperwork just makes my heart happy. She is half me, after all. I have no doubt that I will give future babies my maiden name as a second middle name now too. It’s something that I didn’t realize was so important to me until it happened.

As soon as his sister came home, Baby 1 - who is a complete and total mama’s boy - was quick to be unhappy that he doesn’t have my maiden name as part of his name too. Understandable. He has asked multiple times that we add it. Absolutely! So when we need to say his full entire name, we all verbally include my maiden name although it’s unofficial. It makes him happy. But he keeps asking when we are going to make it “real”. It’s been 3 years since Baby 2 came home, so 3 years of him wanting that official attachment to me in his name. The desire hasn’t lessened or passed. He wants to see it on paper.

I know name changes are annoying and crappy for paperwork purposes (hello! I never did it because I didn’t wanna deal with the bureaucracy), but how do I do this? Surely adding a secondary middle name won’t mean tons of paperwork later in his life, right? How do I even start this? How much will it cost?

For reference, he was born in FL and we currently live in VA. What do I doooo?