Help I am having a bit of trouble?

I have known three latina girls my whole life and I have always known them by their nicknames (Mousey, Sissy and Lupe (Lop-pee)). I know what Lupe's real name is (Guadalupe) but I have no idea what Mousey and Sissy's real names are. They both live out of state and the only one I am still in contact with is Lupe (she has lived next door to my brother Anthony for 10 years now). I would feel like a complete fool if I asked Lupe what her sister real names were so that is where I need help...if anyone can find out what the Mexican names of Mousey and Sissy are, that would be awesome (I went to google and ask.com but they were no help what so ever)