OOh I love all your names! Cora has been a secret like of mine for years - also like Nina - any good?
Of the 4 names you listed, I'd say no to Katherine personally. That's my name and have had years of misspelling (although your dd might not get that if she's a Kitty?) - and much as I love Florence, I really hate Flo which it might end up getting shortened to?
Harriet and Margot I love!
Also love Cecily/Cecilia.
Alice is lovely - no reason why you can't use it this time if it's your number one? I know 2 sisters where the parents did this and they love that connection!
And Stanley - it's the only name I heard after we named ds that I wished we'd used..... :-)
I would say Katherine but I don't think Katherine Pearlgoes, but then if you're not hyphenating I don't suppose it really matter. Florence Pearl just rolls off your tongue but Florence is becoming tedious now, There are not many baby Katherines about now. However I also love Margot Pearl. I just don't like the sound of Harriet. I agree about Ruby being a difficult MN. It'd more suited as a FN but if you really wanted to include it. Have you thought of Ruby Pearl. Or giving her 3 names Eg Margot Ruby Pearl Katherine Ruby Pearl Florence Ruby Pearl Harriet Ruby Pearl.
Harriet pearl (hetty/hattie/Etta/harry) - like Florence pearl (florrie) - like Margot Lois (Meg/Maggie) - dislike, both faddy and harsh names Katherine pearl (kitty) - like the names but Kitty is too cattish for me.