Powerpivot: compiling revenue from different sources?

I'm using 64-bit Excel2010 and want to utlilize Powerpivot to facilitate aggregation of invoices reported in rows from different business units in my company. To date, it's been an exercise in manually setting up the columns and data in each of the speadsheets into a common format and then copy/pasting everything into a single spreadsheet in order to perform a pivot table analysis.(Yes, I have a sense that I'm probably doing things the long way.)

I also have a sense that I might be able to streamline the process with Powerpivot; however, Powerpivot relationships have this "many-to-one" requirement, which my sheets don't have. Rather than relate different fields like "order code" and "order type", I instead want to aggregate revenue data from different sheets; these sheets have some congruent fields, but also have non-overalpping fields and different layouts. I guess one way to look at it is that I'm trying to stack a bunch of boxes of diffferent sizes, but line up one edge of all the boxes so that I can measure the total height of the stack (i.e. height = total revenue). Am I trying to create "junction tables" here and therefore am unable to employ Powerpivot for this?

Thanks in advance for any reply, including links to related training or posts.