We love the name [name]Celia[/name] but really want to use [name]Portia[/name] (g grandma name) for a middle name…does it sound really bad together? Does [name]Cecelia[/name] [name]Portia[/name] sound better?
[name]Hi[/name]!
[name]Celia[/name] is gorgeous (and [name]Portia[/name] is lovely, too…)! [name]Celia[/name] [name]Portia[/name] isn’t exactly ideal, but it isn’t too sing-songy for me (seel-ya/seel-ee-a por-sha is much better than something like seel-ya/seel-ee-a por-tee-a, at least!). Usually, I stay away from middle names that end in the same sound as the first name, but it works in some cases… Besides, you don’t use your middle name as often, and it’s great that the middle name has some meaning for you. 
I think that [name]Cecelia[/name] [name]Portia[/name] has a slightly better flow, for some reason (I prefer the [name]Cecilia[/name] spelling, though)… However, if you love [name]Celia[/name] more than [name]Cecelia[/name], then I would just stick with [name]Celia[/name] [name]Portia[/name]. Or, you could also use two middle names, with one name in between [name]Celia[/name] and [name]Portia[/name]…
Another variant is [name]Cecily[/name], and I think that [name]Cecily[/name] [name]Portia[/name] is gorgeous (despite the username, [name]Cecily[/name] isn’t my real name, but I’m still a bit biased…)! There’s also [name]Celeste[/name], [name]Celestia[/name], and [name]Celestine[/name] (in that case, I actually prefer the flow of [name]Celestia[/name] [name]Portia[/name] over [name]Celeste[/name] [name]Portia[/name]…).
Also, you could also use a different way of honoring your great grandmother. For example, you could use her birthstone, birth flower, favorite flower, middle name, maybe her surname…
But, if you love it, go for it!
Good luck!
This was my initial thought.
[name]Stephanie[/name]
In my opinion, [name]Cecelia[/name] [name]Portia[/name] is far better than [name]Celia[/name] [name]Portia[/name], but neither has a great flow.
Adding another middle name into the mix couls help smooth things out. For example:
[name]Cecelia[/name] [name]Madeline[/name] [name]Portia[/name]
[name]Cecelia[/name] [name]Elizabeth[/name] [name]Portia[/name]
[name]Cecelia[/name] [name]Katherine[/name] [name]Portia[/name]
[name]Cecelia[/name] [name]Eleanor[/name] [name]Portia[/name]
[name]Cecelia[/name] [name]Josephine[/name] [name]Portia[/name]