How do I only keep data from a 6 months rolling period?

Copper Contributor
I have data that has the names of employees on the A column and on the top of the rows are days. I have one sheet for every month.

The values where the rows and columns intersect are numbers with up to 1 decimal.

But in column C I keep a total of that month's values per employee.

In Column D I keep values for the past 6 months (Referencing a sum of the values of Column C for this and 5 previous months.

But, if I have to add or remove employees, I have to do it on every single sheet or it will throw off my formula and they will be referencing the wrong row that their data is on.

How can I avoid the work of adding and removing the agent from all sheets? What different formulas can I use?
2 Replies

@Dragon_Claw 

To answer your questions, you must attach your sample file. 

@Dragon_Claw 

You can use SUMIF or SUMIFS formula with the condition for matching the employee name from column A. 

If you upload a file with some sample data, you will get a better solution in this forum.