I love Constance, it’s a fave name of mine (I know two, one who’s a Coco, the other is a Connie, but I like the suggestion of Tansy too).
For the “perfect” set, I would go for something shorter to tie with Dove - fewer letters I mean - a non-C name, as again Dove very different.
Maybe (though only some shorter):
Avalon
Meadow
Summer
Temperance
Hazel
Aster
Aurelia (you could use Goldie as nickname for Aurelia given the meaning!)
Elspeth
Verity
Florence
Flora
Lydia
Indigo
Mabel
Iris
Zoe
Violet
Margot nn Maisie
Aurora
However, I always think beautiful name before “perfect” sibset (unless it’s so different to significantly affect the child). And I really love Constance!
I adore [name_f]Constance[/name_f], it’s so so pretty! I fell in love with it when I fist read The Three Musketeers. I think D, C, C initials are very okey.