I think [name]Posy[/name] is listed as a possible alternative to [name]Rosy[/name], which indicates any name [name]Rose[/name] or compound name of [name]Rose[/name] would work. [name]Rosemary[/name], [name]Rosemarie[/name], [name]Rosalie[/name], [name]Rosalind[/name], [name]Rosamund[/name], etc. I’m not sure it won’t get her called [name]Rosie[/name] or [name]Romy[/name] in some cases.
There doesn’t seem to be much to work with unless someone just thinks of them, but I also see that [name]Josephine[/name] - where do you get [name]Posy[/name] from that. At least [name]Posy[/name] rhymes with [name]Josie[/name], it also rhymes with [name]Rosie[/name], so it shouldn’t be that difficult to attach the nickname [name]Posy[/name] to another name, especially a floral name. Any other names with an ose syllable? [name]Cosette[/name] comes to mind, [name]Posy[/name] so they don’t call her Cozy.
Also, I am trying to look into names that start with a po sound - not too many! Maybe something of [name]Paula[/name] - [name]Pauline[/name], [name]Paulette[/name], I think could go [name]Posy[/name]. Or [name]Polly[/name]. I kind of like the ‘Ballet Shoes’ [name]Pauline[/name]/[name]Posy[/name] relation there, unfortunately leaving out [name]Petrova[/name] though. (children’s novel by [name]Noel[/name] Streatfeild, later made into a movie or two).
I think [name]Penelope[/name] might be kind of a stretch, but what someone calls you every day may have nothing to do with your name. You could name her [name]Isabella[/name] (random non-posy name) and pet name her [name]Posy[/name], and that should stick, at least until she can read and think to try out another more obvious nickname. Same with [name]Rose[/name] names and other -ose names.
I think it was [name]Kristen[/name] who really liked the name [name]Apolline[/name] - a[name]POlline[/name] > [name]Posy[/name]. I saw a name in the P names for girls, [name]Piroska[/name], Hungarian variant of [name]Priscilla[/name]… I think it’s too exotic unless you’re actually Hungarian, but it made me think there must be other names that just look like you could just take [name]Posy[/name] right out of there and it wouldn’t be a stretch. Names that begin with other letters like [name]Apolline[/name], or name with a ‘p-os’ in them that are currently impossible to search for!
Trying to help, hope you got some ideas for your friend.