Allocating expenses using a 4 week/5 Week accounting calendar

Hello,
Wondering if anyone out there can easily assist me. I'm trying to allocate expenses throughout a fiscal year and the way the accounting calendar is set up, any regular month is 4 weeks long, and any quarter end month is 5 weeks long, thus still making it 52 weeks in the year. What makes this difficult is that there is one center that is opening up in beginning of May and another that is closing end of June. I'm trying to formulate is so that a store, either opened all year or part of the year, will all be charged the same amount while they are open. please let me know if anyone needs more info or has no idea what I am talking about.

THANKS!!