Rosamund is very pretty, although I prefer (and love!) the French form,
Rosemonde.
Some other
Rose- names:
Rosalind /
Rosalinda/
Rosaline /
RosalynRosanne /
RoseanneRosanna / Roseanna
Roswitha (I love this- it's very different, and comes with a neat namesake)
Rosalia /
RosalieRosabella /
Rosabel
Personally I like the nns
Rose and
Rosie /
Rosy, but if it would cause confusion with other relatives, you could just ask for her not to be called that. There's always
Rosa (like you said) and
Ros /
Roz. I also like
Romy, and
Roma.
For
Rosalia /
Rosalie, you could use the nn
Allie or
Ali. For all of the
Rosanne names, you could use
Annie, and for
Rosalind, you could use
Lindy.
Shannon