I really like
Roberta! I don't usually go for feminized versions of male names, but
Roberta works a lot better than, say,
Geraldine or
Thomasina (probably because it doesn't *sound* like
Robert).
A few combinations that may work (sorry if I include some you've already included):
Roberta MildredRoberta SophieRoberta JuneRoberta ChristineRoberta Blaire
Roberta Ursuline
Roberta LouiseRoberta Parthenope Roberta JessamineRoberta DelphineRoberta IngridRoberta Gudrun
*Formerly summitseeker*--Still seeking summits--