hmmm, I call a few of my aunties "mai" leh...I think, the ones older than ur parents (eg, if it's ur father side one, then the aunty older than the father) will be addressed as "nien", and the one that's younger will be addressed as "mai"...
I'm not sure about "Kim" and "Peh", coz I call my eldest aunties (both ma and pa side) "Peh4 Nien3", 2nd aunties "Ji3 Nien3", "Ta Nien" etc...as for "Kim", I'm not sure leh...