Too royal?

I would choose Elizabeth and any variation of Kathryn/Katharine/Catherine etc. Just be warned that the first will almost always be misspelt (it's my mother's name) but my middle name (Catherine) is usually spelt correctly. In any case, the Royal Catherine is usually called Kate, isn't she?

Camila, Catherine and Elizabeth sound like a very respectable set of siblings!

Eliza is your best bet. I wouldn't think 'royal' at all if I heard of a Camila and Eliza combination.

I wouldn't use the Kathryn spelling.

I think you should choose the names you love, as another PP suggested, by the time your DDs are at school, I don't think you'd have to worry about associations with the RF, especially if you use the shortened names for some on your list.

However, using some of other names on PPs lists plus your own choices: ( Helena, Margot, Annabelle, Eliza, Kathryn ( with all the variants of Katherine/Kathryn to choose from) would be lovely too and not as noticeable to most, or be as commented on, as you might think.

Apart from Zara they are all classics and often go together

from your list I love

Kathryn
Elizabeth
Elspeth
Eliza

Choose the names you like best. They are all nice names, but my favourites are Philippa and Elizabeth. I personally wouldn’t associate them with the RF, they’re classy and timeless names.

Philippa and Eliza are a gorgeous combination and wouldn’t stand out as royal to me.

Congratulations and good luck! I would just go ahead and choose names you like. The old Queen died more than three years ago. By the time your twins are at school she will be a distant memory for many. With all respect to the current Queen, I don't think Charles will live to the great age of his mother, so Camilla will cease to be a royal name in most people's minds within the next 20 years. Katherine and all its variant spellings is a timeless name with lots of other associations other than the Royal Family. Kathryn is not a spelling any royal person has ever had as far as I know. Elizabeth is another classic name.

I’d go Philippa and Elspeth or Philippa and Eliza.

definitely not Zara and Elizabeth lol.

other suggestions

eloise
clara
margot
beatrix
vivienne
francesca
eva/ evelyn
harriet
grace
helena
jemima
matilda
annabelle

If I saw Camila and any other 2 names on your list I would think you were a massive royal fan I'm afraid. On their own they're fine and lovely, but together they make a theme because Camila is not that common these days. Depends how much that bothers you of course, they are also all lovely names. I think Camila, Philippa and Elspeth would be the least royal coded and wouldn't bring that association to mind, and sound really nice together?

Alternatively how about these which to me are classic but not recently royal: Florence, Imogen, Clementine, Rosalind, Margot, Annelise, Helena, Adelaide, Cecily, Thea.

You might be better asking on the Baby Names section. 🤷‍♀️