Array function for date(month), Range Date(month)

Hello Excel Experts,

I have a quick question and wonder if there's a solution to it.

Given a unique key, i.e. Promo Name, as well as the start and end date of the given promo name, is there a way to have excel to automatically fill in the date ranges?

i.e. Promo Name has a start date of Jan 1, 2012 and and End Date of Apr 30, 2012.

Would it be possible to automatically fill in the rows of cell, from Jan 1, 2011 (1 year BEFORE the promo date) and Apr 30, 2013 (1 year AFTER the promo date). Thus the answer would look like this (below)

Jan, 2011
...
...
... 1 year before promo
...
...
Jan, 2012
...
...
... During promo period
...
...
Apr, 2012
...
...
... 1 year after promo
...
...
Apr, 2013

Note!!! Promo period varies...it can be 1 month - 12 months...thus, it'll be very dynamic...thus, the number of rows filled varies as well.