Filter a rollup workbook by month with data from other workbook

I am trying to filter the rollup data by month.

I edited this workbook(very close to biz version). Live its a rollup workbook on its own and each store is its own workbook on a sharpoint so each can load their own data. 6 stores.
So I know some forumla need to be specific if they need to load external data.

What can I do to the rollup sheet to just display feb data or then March data.

Thanks
Dennis