What's in a name?

The first of my editors got their final notes and edits to me late last night. They included a lot of helpful suggestions and revisions, so I think that editing is looking really promising right now! Unfortunately, one of their best suggestions is one that is nearly impossible for me. My main character is named Renee (nickname Ray) and her sister is Raven. The setting of the first book is a village called Rayai. All three of these, as it turns out, begin with "Ra".

With my synesthesia, their names are entirely distinct colors that are simple to differentiate. It wasn't until they'd had those names for five years before anyone told me that they were easy to mix up. Since then, I've been told the same thing by several other people. To be honest, I think that they have an excellent point, and I actually want to change the name--so, what's the problem?

For me, names define characters. Not in any way that someone else could probably see--well, unless they could mysteriously borrow my synesthesia for a few hours. To change a character's name is the same, on a visceral level, as erasing that character's existence. The character won't--can't--be the same person if they have a different name.

Of course, this probably sounds ridiculous. What's in a name, anyway? Can't I just use find and replace to fix it? Those are the things that I keep telling myself, but it's so much harder than that. If you've known someone for ten years, suddenly relearning their name is very hard indeed. When asked by that person to do so, of course, I will (and have); when you're the one renaming them, it feels much more uncomfortable.

So, what do you think is in a name?