I think you’d have less problems spelling it [name_f]Carys[/name_f]. I also think it looks better. I didn’t know that the correction spelling was [name_f]Cerys[/name_f], I always just thought it was [name_f]Carys[/name_f]. So I can see how knowing that would bother you. I guess it just depends if you’d rather be correcting people (which could still happen with [name_f]Carys[/name_f]) or know that it’s a “made-up” spelling (although pretty legitimate at this point).
[name_f]Cerys[/name_f] [name_f]Emily[/name_f] is beautiful. Mispronunciation can always be corrected, and if you’re doing it with [name_u]Rhys[/name_u] already, she wouldn’t feel left out!
I really appreciate that as an American you understand the true pronunciation of my own name and dont try to argue it 
Over here in [name_m]Wales[/name_m], [name_f]Cerys[/name_f] and [name_u]Rhys[/name_u] would be the perfect sibset, so I dont see it any stranger than any of your kids names at all
Congrats! Must feel good to have a name settled. I love all your kids’ names. I do think [name_f]Cerys[/name_f] is more likely to be mistaken for a soft C than [name_f]Carys[/name_f] (which isn’t likely to be mispronounced at all). But I totally get using the spelling that feels more authentic. I don’t think you should change the spelling from the name you feel connected to and that feels right for you. It’s an easy enough correction to make. Of course, you should maybe take the advice of those who have had to constantly correct people their whole lives over mine. As an [name_f]Emily[/name_f], I haven’t run into much trouble.
I agree that, since you’re in america, you will have lots of problems with people mispronouncing [name_f]Cerys[/name_f]. And just something to consider, you will be correcting people throughout your daughter’s childhood, but she will have to her whole life. in the end, you need to do what you feel most comfortable doing.
My mom’s family is Welsh, but I honestly just love the names. I feel like they often hit that sweet spot of being unique but recognizable.
We are in the southern US and have a [name_f]Carys[/name_f] (MN ”yra) and we get nothing but compliments. One person has said “Carries” but people tend to let me say it first. I love her name so much. Fits her perfectly! I think the [name_f]Cerys[/name_f] spelling is lovely and while I suspect there might be slightly more mispronunciations I’d guess it wouldn’t be any worse than [name_u]Rhys[/name_u] (another name we love and have saved for future boys!) which you’re used to.
I like it a lot!
My cousin is a [name_f]Cerys[/name_f] (British but lives in [name_f]Canada[/name_f], she’s 9) and it works fine for the most part. She does get called [name_u]Kerry[/name_u] / [name_f]Cerise[/name_f] occasionally but when people know how to say it, it’s easy enough to remember. The only time it bothered her was when somebody misheard it as ‘carrots’ 
I love it! Beautiful name. I don’t think it sounds made up and is great with her siblings names.
Thank you! I’ve been told that it’s way too close to [name_u]Rhys[/name_u] to use. [name_f]Do[/name_f] you think that’s true?
No! If the emphasis were ca-RYS, then maybe, but it’s not. To me this is no different than, say [name_m]Oscar[/name_m] and [name_f]Caroline[/name_f], or [name_m]Nathan[/name_m] and [name_f]Annabelle[/name_f]: if the syllable is accented in one name and unaccented in the other, it keeps from sounding too matchy. Your names go beautifully!
I don’t know how to pronounce it.
I feel like it’s too similar to [name_u]Rhys[/name_u] for some reason. I know they sound different, but they look a lot alike. And if people pronounce it “sair-reese” then they almost sound like the exact same name. [name_f]Carys[/name_f] might get pronounced wrong too though, there’s no guarantee either way. But choose the name you like best and use the spelling you like best. I personally wouldn’t use it with a brother [name_u]Rhys[/name_u], but that doesn’t mean you shouldn’t.
I don’t think [name_f]Cerys[/name_f] and [name_u]Rhys[/name_u] are matchy at all. As a previous poster said, the emphasis is different so I don’t see any problem.
I didn’t know that [name_f]Cerys[/name_f] was the more authentic spelling! [name_f]Carys[/name_f] is in regular use in [name_m]Wales[/name_m] and [name_f]England[/name_f] (#299 vs. [name_f]Cerys[/name_f] #225 in 2012) so I think it’s a perfectly legitimate spelling variation at this point. Personally I would use the [name_f]Carys[/name_f] spelling to make the pronunciation issues easier, but either way I think it’s a lovely name that goes perfectly with your other children’s names Best of luck!
I have a [name_f]Carys[/name_f] [name_f]Louise[/name_f]! I find [name_f]Carys[/name_f] would be easier than [name_f]Cerys[/name_f] because I would wanna make an “S” sound ! [name_u]Love[/name_u] the name though 
Lol also a southerner with a [name_f]Carys[/name_f] and I’ve had people say carries lol. They usually let me say it as well and I say it rhymes with [name_u]Paris[/name_u] and they get it lol
I know not one, but two people with a name pronounced as KARE-iss (rhymes with [name_u]Paris[/name_u]) and both are spelled [name_f]Charis[/name_f].
Have to admit, I immediately thought [name_f]Cerys[/name_f] was pronounced SUR-EESE, [name_f]Cerys[/name_f] looks better, but [name_f]Carys[/name_f] is easier if you want the CARE pronounciation.
I agree with above. [name_f]Carys[/name_f] for Care-iss.
[name_f]Cerys[/name_f] [name_f]Emily[/name_f] is lovely. I do like it much better than [name_f]Cerys[/name_f] [name_f]Emmeline[/name_f].
I think you will have as much issues with [name_f]Cerys[/name_f] as you have had with [name_u]Rhys[/name_u].
However, it still doesn’t seem like you love this name.
I still think [name_u]Rhys[/name_u] and [name_f]Cerys[/name_f] are too similar to use together, but that is personal preference. I feel like your best bet would be to find another name similar to [name_f]Heidi[/name_f]. I still love [name_f]Elsa[/name_f] for you. Maybe [name_f]Ingrid[/name_f]? I want to recommend [name_f]Elsie[/name_f] or [name_f]Elise[/name_f] or [name_f]Greta[/name_f] or [name_f]Gretchen[/name_f] but they are all too similar to your kids names.
If you do love [name_f]Cerys[/name_f], then congrats on finding a name. If not, then there is nothing wrong with you still looking.
I also know a little KARE-iss (rhymes with [name_u]Paris[/name_u]) spelled [name_f]Charis[/name_f].