Tell her this is the most special birthday ever because it only comes every four years. She is one of a few very special people who have this birthday!
On the Leap Years break out the biggest celebrations possible.
When people say to her, "oh you poor thing, you only have a birthday every four years" make sure and correct their mistake. She is extremely lucky to have this very rare and wonderful birthday!
On the years when there is no Leap Day celebrate for the entire week beginning with February 28th and roll on through March 6th. This makes up for the lack of the 29th.
Remember that she will encounter odd issues like not being able to actually fill in her real date of birth on forms that don't have the 29th as an option. Teach her to insist on having her REAL date of birth listed no matter what.
I've lived on the Earth for 57 years but I've had 14 real birthdays. But because my mother told me from the time I can remember how special this was I have grown up feeling fortunate. And yes, last week was a rolling birthday party here on November Hill.
Can you even imagine how huge the party will be here on November Hill in 2020 when my numbers hit 60 and 15? Something to look forward to, for sure. :)