How should I celebrate Ilsemarie's birthday?

For those days, I have been thinking how I should celebrate Ilsemarie's birthday. Ilsemarie Straub is my German friend with whom we have been exchanging emails for over 10 years. She is a travel journarist who lives in a little town near Hanover named Barsinghausen. In 2007, my wife Ayako and I visited her and her family with Ayako's sister Masako and her husband Yasuhiro. We stayed with them at Barsinghausen for three days. Ilsemarie has a husband,two sons and a daughter. Her family were all very kind to us, though we couldn't see her daughter because she worked in former East Germany. Ilsemarie showed us around not only Barsinghausen, but took us to Hameln which is famous for a legendary tale of "Pied Piper of Hamelin."
Ilsemarie's birthday is March 3rd. She says this year's birthday is special for her, because it will be her "60th year plus 120th month" birthday. A humourous expression, isn't it?