How to create and combine 4 reports, one being a total off fields from the other 3 ?

If I have one rdl.. and I need 4 reports in it, one has a table that is a summary off certain fields from the other 3. I have some questions then

1) How do I add 4 reports to the same report so that I end up with 4 Excel tabs?

2) How can I relate a 4th report to be a summary report of all 3 other reports in the same rdl?

My Excel file in the end will have 4 sheets. 3 of them will be reports, and the final will be a summary table that sums up certain fields based off the other 3 reports. I am not sure the approach to both create the 4 reports together, then ensure pageination is correct in that I end up wtih 4 sheets in an excel workbook when doing an export in the end. You gave a great explanation but now I have more questions :)

Please also reference: http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=233219&SiteID=1&mode=1

I responded on the original thread:

http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=233219&SiteID=1&mode=1