Don't you have a nice uncle
Will or
William to name her after? :)
The lovely thing about a nice classic name like
Mary is that is has lot of variants, maybe this:
Evelynn
Marya RoseEvelynn
Mairwen RoseEvelynn
Marion Rose (I'm loving this one)
Evelynn
Mia RoseEvelynn
Marianne RoseEvelynn
Moira Rose
Or change
Rose:
Evelynn
Mary RosamundEvelynn
Mary RosalindEvelynn
Mary RosaliaEvelynn
Mary RaisaEvelynn
Mary RosabellaEvelynn
Mary Roxanna
Actually it's more of an added positive that your sister has a name too.. Does she have both of
Mary and
Rose, or just one?
Some other ideas:
Evelynn
Mia RosalindEvelynn
Raisa MairwenEvelynn
Marya RomyEvelynn
Rosalia MarisolEvelynn
Marion RosamundEvelynn
Rozanne Marzena