I really like Caroline. It would be an honoring name for a Charles and Carol for me. I prefer the long i rather than the short (which I prefer to spell Carolyn). Either vowel sound for the first vowel works for me.
If I were to use Caroline, I like the idea of the nickname Cara.
Caroline Wren is nice. I like seeing Wren. Caroline and Hazel could definitely be sisters. Similarly warm and comfortable, worn-in calico sheets on the line type of names.
Combos:
Caroline Susannah
Caroline Daphne
Caroline Elise
Caroline Alice
Caroline Gloria
Caroline Rhoda
Natalie Caroline
Julia Caroline
Susannah Caroline nn Sunny (one of my pet combos haha)
Siblings:
Nolan
Bennett
Anthony
Lydia
Harriet
Bridget