We are expecting our third in [name_f]May[/name_f] and do not know the gender. We already have a girl, [name_f]McKenna[/name_f], and a boy, [name_m]Miles[/name_m]. We REALLY struggle with names as we tend to like completely different styles, but our top contenders right now are [name_f]Lucy[/name_f] [name_f]Catherine[/name_f] for a girl and [name_m]Simon[/name_m] [name_m]David[/name_m] for a boy. I love both, but worry that that don’t “go” with the more modern sounding names our other children have (more so [name_f]McKenna[/name_f] than [name_m]Miles[/name_m]). Honest thoughts? Thanks in advance!
While matching siblings’ names isn’t the most important thing in the world, I do completely understand your concern. Personally, I think a lot about potential sibling names when I put a name on my shortlist - it has to have a similar “feel” to other names I like, and it can’t have really similar sounds to any of my other favourites (e.g. I’d only use one of [name_f]Astrid[/name_f] and [name_f]Ariadne[/name_f], or [name_m]Leo[/name_m] and [name_u]Theo[/name_u]).
In your situation, you’ve already given very different style names to your two children, but both start with the letter M so there is a subtle link between them there. I’d maybe either try and find a name that falls between modern (like [name_f]McKenna[/name_f]) and traditional ([name_m]Miles[/name_m]) for your next, or else use another M- name if you can find one you love.
Examples of names which fall somewhere between modern and traditional:
[name_f]Lilly[/name_f]
[name_f]Aria[/name_f]
[name_u]Seren[/name_u]
[name_f]Lola[/name_f]
[name_f]Georgia[/name_f]
[name_f]Isla[/name_f]
[name_f]Leah[/name_f]
[name_m]Ethan[/name_m]
[name_u]Owen[/name_u]
[name_u]Dylan[/name_u]
[name_m]Leo[/name_m]
[name_m]Bastian[/name_m]
[name_u]Evan[/name_u]
[name_m]Samson[/name_m]
More M- names:
[name_f]Madeline[/name_f]
[name_f]Mila[/name_f]
[name_f]Mia[/name_f]
[name_f]Margot[/name_f]
[name_f]Minnie[/name_f]
[name_f]Mabel[/name_f]
[name_f]Maren[/name_f]
[name_u]Max[/name_u]
[name_u]Morgan[/name_u]
[name_m]Matteo[/name_m]
[name_u]Micah[/name_u]
[name_m]Malachi[/name_m]
[name_m]Maddox[/name_m]
[name_u]Mason[/name_u]
Or, you could just use a name you love regardless of how well it “goes” - very few people would bat an eyelid at [name_f]McKenna[/name_f], [name_m]Miles[/name_m] and [name_f]Lucy[/name_f] or [name_f]McKenna[/name_f], [name_m]Miles[/name_m] and [name_m]Simon[/name_m]. Both of the names you’re considering are lovely and I don’t think it necessarily matters if the three of them together make for an unexpected trio. Each child is an individual and won’t be seen as part of a “sibset” for the greater part of their lives, so I think it’s fine just to name each separately.
I love both [name_f]Lucy[/name_f] and [name_m]Simon[/name_m], but I agree they don’t really go with [name_f]McKenna[/name_f] and [name_m]Miles[/name_m]. They could work with just [name_m]Miles[/name_m], but I think [name_f]McKenna[/name_f]'s significantly more modern sound doesn’t quite work with the classic [name_f]Lucy[/name_f] and [name_m]Simon[/name_m]. That said, I don’t think anyone will like, call you out on having names of different feels/styles! You should go with what you love. I thought of two options similar in sound to [name_f]Lucy[/name_f]/[name_m]Simon[/name_m] but that I think mesh better with [name_m]Miles[/name_m] and [name_f]McKenna[/name_f]:
[name_f]Luna[/name_f] [name_f]Catherine[/name_f]
[name_m]Silas[/name_m] [name_m]David[/name_m]
[name_f]McKenna[/name_f], [name_m]Miles[/name_m], and…
[name_f]Clementine[/name_f]
[name_f]Imogen[/name_f]
[name_f]Mercedes[/name_f] ([name_f]Sadie[/name_f])
or
[name_m]Maxwell[/name_m]
[name_m]Roman[/name_m]
[name_m]Samson[/name_m]
Personally, I really think trying to match the style of sibling names is misguided - they’re not going to live as part of a set their whole lives but as individuals, and they each deserve the best name you can give them, individually. If there are names you love equally it could make sense to use whichever “goes” best as a tiebreaker, but not between names you love and names you just like. [name_f]Lucy[/name_f] and [name_m]Simon[/name_m] are lovely - use them!
I agree with the first two posts for sure. [name_f]Lucy[/name_f] and [name_m]Simon[/name_m] ARE different stylistically from [name_f]McKenna[/name_f]. But [name_f]Mckenna[/name_f] and [name_m]Miles[/name_m] were already different, so whatever you choose is going to have to be more similiar in style to one name or the other. So go with your heart! Besides, it’s not a super harsh glaring difference, and as a group, [name_f]McKenna[/name_f], [name_m]Miles[/name_m] & [name_f]Lucy[/name_f] or [name_f]McKenna[/name_f], [name_m]Miles[/name_m] & [name_m]Simon[/name_m] actually sound good to me because of the phonetics.
P. S. My first thought was, maybe [name_f]McKenna[/name_f] is a family name, and then, I wonder if they are in the UK. 
Because I could totally see either of these groups as a cute little [name_u]London[/name_u] or [name_m]Dublin[/name_m] trio, with older sister having the tradition of a family surname. 
I agree with the others. Go with what you love. My brothers and I have a sorta different style names. As mine is more Spanish, but people got used to us being a set as kids. And it caused our names to be linked together anyway. [name_f]Lucy[/name_f] and [name_m]Simon[/name_m] are lovely.
As a Dub, I feel I have to point out that [name_m]Dublin[/name_m] in not a part of the UK. 
however I get what you mean, they do have a British/Irish feel to the sibset.
I think go for it. They aren’t terribly far apart style-wise and won’t clash. [name_f]Lucy[/name_f] and [name_m]Simon[/name_m] are lovely.
Thank you all so much for all your honest and thoughtful feedback! It really does help to hear unbiased opinions!