–Awaiting Baby Kate?
I do suspect that a young Kate will be called Katie a lot. With no other obvious choice for a nickname, people will jump to the well-known Katie without even thinking about it.
As with other dilemmas like this one, the issue becomes: How much will this bother you? With family and friends—people who see your daughter a lot—you can politely insist on Kate-not-Katie. They'll eventually get the message and stick with Kate (unless they’re deliberately trying to be obstinate).
Yes, I'd definitely notice the similarity, and call these names too close for comfort. As you mention, they actually don't share many letters in common, which makes them look distinct when written down. But the similar sound is more than enough to trip everyone up and cause confusion, especially since you're not trying to name your daughter after her mom.
–Author in a Crisis
As I've often said, style is in the eye of the beholder. So the Name Lady is not here to give you a thumbs-up or down on what name is right for your baby—real or literary. But what I can do is help you zero in on that just-right name on your own. The first step is to dig deeper on your initial choice, Holly, to see what qualities in it appeal to you. Then, we can find other names that share those qualities.
So we ended up calling her by her first name—which I hate! It sounds horrible just saying it, but I don't like it. My daughter just turned one. Would it be okay to change her name now? We have a name we both like. I feel silly even considering it, but I'm so in love with this new name.
Since your daughter is a year old, this is borderline territory for a name change. She is too old for you to just switch the name casually, but she is too young to be involved in the decision. However, since you have such a powerfully negative reaction to her current name, it might be healthier to go ahead and make the change.
–Able to Use Abel?
I'm not sure who started the idea that a pattern of three two-syllable names is a problem, but I don't think it is. Like so many "rules" of naming, it is a preference that somehow grew into a prohibition.
Hundreds of girls every year are given names like Campbell and Elliott, and we've all heard of starbaby girls named Wyatt and James. So a girl could certainly "pull off" McKade. The "McK" lead-in may have started out as a surname-influenced masculine name style, but these days it's used almost exclusively for girls: McKenzie and McKenna, as you mentioned, but also McKayla and McKinley, plus spelling variations of these, are all girl today—and all quite popular.
–Surprised Boy Mama
When you thought your son was a daughter, you imagined an Iris and all the qualities that name conjured for you: Radiance, perhaps; or blooming purple flowers, or rainbows, or Greek myths. Or maybe no images in particular, but the sense of a daughter, a girl called Iris who would take her place in your home.
While Gibson is a rare name, I wouldn't call it odd at all. It is used as a first name: It's ranked among the top 1,000 names for boys for the last several years. About 250 new baby boys in the U.S., per year, are named Gibson (and so are a handful of girls!).
Gibson is a fresh twist on a fashionable style, being a surname with a –son ending. That means it's a classic recipe for an attractive name. The fact that it has both a family connection, and a musical one, and you like the nickname? That’s a smash hit.
First, let's forget about spelling the name differently. How many people even know for sure how Flynn Rider's name is spelled? More importantly, how often will people first encounter your sons as a pair on paper, vs. spoken aloud—where the spelling doesn’t matter? So unfortunately, you can't spell your way out of this dilemma.
Oh, dear: This is more of a relationship dilemma than a naming dilemma. At least in the U.S., choosing a baby’s name is considered a joint decision—but of the baby's parents, not the mother and grandmother. Asking for a grandparent's opinion is one thing. A grandparent who feels like she has the last word on the pick is quite another.