At my chapter we call them Carnation sisters, but to make it shorter we stick with big/lil and in fact my family calls the older ones grandma and great grandma, etc. I guess mostly as a term of endearment, but also sarcasm, since compared to my 18 yr. old grandlittle, I seem ancient, but still have lots of Phi Mu wisdom to pass on...like our biological Grandmothers.
So to answer your question, technically they are called Carnation sisters.
tara
---to practice day by day
love, honor, truth---