Sum up data in rows based on dates in column headers - PowerPivot

Dear All,

I'm working on connecting data from two large datatables with sales data. Both tables are connected in Power Pivot through "Product Name" column.

In one of the tables I have product names and actual sales data by day in following format:

table_1.png

I have second table with Client Names, Product Names, specified periods of promotional activities and forecasted sales looking like this:

table_2.png

I need to compare forecasts with acutal data and be able to filter the results by product, client and time period. I am not able to figure how to sum the day by day actuals (first table) to automatically compare them with periods and forecasts from second table.

Would appreciate any help! Please let me know if something is not clear enough!

PS This is my first post here, so nice to meet you