As [name_f]Daisy[/name_f] is a nickname for [name_f]Margaret[/name_f] and you already have [name_f]Margot[/name_f] covering that, I might try to find a way to get [name_f]Sue[/name_f] in there.
You could always go with a variation of [name_f]Susanna[/name_f]:
VARIANTS: [name_f]Sukie[/name_f], [name_f]Susie[/name_f], [name_f]Suzi[/name_f], [name_f]Suzie[/name_f], [name_f]Suzy[/name_f], [name_f]Zanna[/name_f]
OTHER LANGUAGES/CULTURES: [name_f]Sawsan[/name_f] (Arabic), [name_f]Susanna[/name_f], [name_f]Susannah[/name_f] (Biblical), Sousanna (Biblical Greek), [name_f]Shoshannah[/name_f] (Biblical Hebrew), [name_f]Susanna[/name_f] (Biblical Latin), [name_f]Suzana[/name_f] (Croatian), [name_f]Zuzana[/name_f], Zuzanka, Zuzka (Czech), [name_f]Susanne[/name_f], [name_f]Sanne[/name_f], [name_f]Susann[/name_f] (Danish), [name_f]Susanna[/name_f], [name_f]Suzanne[/name_f], [name_f]Sanne[/name_f], [name_f]Suze[/name_f] (Dutch), [name_f]Susanna[/name_f], [name_f]Sanna[/name_f], Sanni (Finnish), [name_f]Suzanne[/name_f], [name_f]Suzette[/name_f] ([name_m]French[/name_m]), [name_f]Susanne[/name_f], [name_f]Susann[/name_f], [name_f]Suse[/name_f], [name_f]Susi[/name_f] ([name_m]German[/name_m]), [name_f]Shoshana[/name_f], [name_f]Shoshannah[/name_f] (Hebrew), [name_f]Zsuzsanna[/name_f], [name_f]Zsazsa[/name_f], [name_f]Zsuzsa[/name_f], [name_f]Zsuzsi[/name_f] (Hungarian), [name_f]Susanna[/name_f] (Italian), [name_m]Zane[/name_m], [name_f]Zuzanna[/name_f] (Latvian), [name_f]Suzana[/name_f] (Macedonian), Huhana (Maori), [name_f]Susanne[/name_f], [name_f]Susann[/name_f] (Norwegian), [name_f]Zuzanna[/name_f], [name_f]Zula[/name_f], Zuza, Zuzia (Polish), [name_f]Susana[/name_f] (Portuguese), [name_f]Suzana[/name_f] (Portuguese (Brazilian)), [name_f]Susanna[/name_f], [name_f]Syuzanna[/name_f] (Russian), [name_f]Suzana[/name_f] (Serbian), [name_f]Zuzana[/name_f], Zuza, Zuzanka, Zuzka (Slovak), [name_f]Suzana[/name_f] (Slovene), [name_f]Susana[/name_f], [name_f]Susanita[/name_f] (Spanish), [name_f]Susanna[/name_f], [name_f]Susanne[/name_f], [name_f]Sanna[/name_f], [name_f]Susann[/name_f] (Swedish)
…or maybe go with an S middle name: [name_f]Sabina[/name_f], [name_f]Sadie[/name_f], [name_f]Sara[/name_f], [name_f]Selina[/name_f], [name_f]Sophie[/name_f], [name_f]Sophronia[/name_f], [name_f]Stella[/name_f], [name_f]Sybil[/name_f], [name_f]Sybilla[/name_f], [name_f]Sylvia[/name_f], Sylvi
… and you can always honour somebody in another way than through their name, maybe your grandmother’s favourite author or composer or book character, colour, city, etc.
My personal favourite middle name for [name_f]Rosamund[/name_f] is [name_f]Clara[/name_f]; from the above ideas my favourite combos would be [name_f]Rosamund[/name_f] Zuza and [name_f]Rosamund[/name_f] [name_f]Sybil[/name_f].