Hi there.
Here are my thoughts on your list-
Ivy-This is nice. It. seems a little lacking next to the bold [name_f]Harriet[/name_f], & probably more popular. A good enough name though. I like the nature imagery, but honestly, sometimes I just hear I.V., like what you get at the hospital.
Margot-I feel like the nns here are a little stretch, but maybe not. [name_f]Margot[/name_f] is.a good solid name that goes well w/Harriet. Getting a bit more popular. I’m personally not wowed by it, but it may be because I just see it on everyones’ list on this board.
Winifred-This seems perfect w/Harriet! [name_u]Unique[/name_u] yet simple, classic, feminine & just the right amount of dusty vintage. I mean that in the best way possible! [name_f]Hattie[/name_f] & [name_f]Winnie[/name_f] for sisters are just 
Penelope-This is a really fun name. It’s well known, definitely more popular than [name_f]Harriet[/name_f], but not top ten or anything. It’s spunky, smart & feminine w/lots of great nns. I like [name_u]Penny[/name_u], but my favorite is [name_f]Nellie[/name_f]! [name_f]Polly[/name_f] or [name_f]Poppy[/name_f] are also good.
Here are a few more ideas that you may like:
Clementine nn [name_f]Minnie[/name_f] or [name_f]Cleo[/name_f]
Dorothy nn [name_f]Dora[/name_f], [name_f]Daisy[/name_f] or [name_f]Thea[/name_f]
Eleanor nn [name_f]Ellie[/name_f] or [name_f]Nellie[/name_f]…kind of popular, but it’s perfect w/Harriet & just a fabulous name.
Ellen nn [name_f]Ellie[/name_f] or [name_f]Nellie[/name_f]
Edith
Esther nn [name_f]Essie[/name_f] or [name_f]Tess[/name_f]
Estelle nn [name_f]Essie[/name_f]
Elizabeth nn [name_f]Eliza[/name_f], [name_f]Ellie[/name_f], [name_f]Elsie[/name_f], [name_f]Bess[/name_f], [name_f]Bette[/name_f] or [name_f]Tess[/name_f]
Emmeline
Gwyneth nn [name_f]Gigi[/name_f] or [name_f]Gwen[/name_f]
Gwendolen nn [name_f]Gigi[/name_f] or [name_f]Gwen[/name_f]
Imogen nn [name_f]Imee[/name_f], [name_f]Idgie[/name_f], [name_f]Ginny[/name_f] or [name_f]Minnie[/name_f]
Ilse
Josephine
Jane nn [name_f]Janie[/name_f]
June nn [name_f]Junie[/name_f]
Kathleen nn [name_u]Kit[/name_u] or [name_f]Kitty[/name_f]
Lilian nn [name_f]Lili[/name_f]
Laurel nn [name_f]Lulu[/name_f]
Margaret nn [name_f]Maggie[/name_f], [name_f]Molly[/name_f], [name_f]Maisy[/name_f], [name_f]Peggy[/name_f] or [name_f]Gerty[/name_f]
May
Mabel
Maple
Olive nn [name_f]Livy[/name_f]
Pearl
Phoebe
Rosalie nn [name_f]Rosie[/name_f]
Vivian nn [name_f]Vivie[/name_f]
Hope this helps. 