Merging Excel Files

Greetings all, first time poster. I am somewhat familiar with excel, but it’s been a while since I've used it. A little background on the project I am working on: At the end of each shift, each employee fills out an Excel spread sheet (equipped with macros, etc, I did not do create this template) as to what they did that day and how long they spent doing it. The spread sheet is set up as for one month. At the end of the month, they submit the file to their supervisor, who then looks at the tally on the last page of the excel file. It shows what parentage of each activity they did was and displays it as a pie chart, bar graph, etc.

What my supervisor wants me to try to do is create a way for him to be able to go into an excel spread sheet (one that I would create) and be able to select say, 3 other peoples monthly logs and display a total for all those selected in the same format as the month end is displayed. Can anyone help me out with what to do? PM your email if you'd like to see a copy of the master log its all based on, if that would help you. I cant get it to upload here. Thanks in advance!