Complex problem on Excel 2007?!?!?!?!?

Ladies & Gents,

I believe to have come accross one of the hardest tasks in Excel.
You must Picture this in your mind. We have the following:

3 Worksheets - within each worksheet there is approximately 2000 rows & on average 27 columns.

What I want to do is, combine all 3 worksheets into 1 worksheet.

However, if you just transfer the data from each worksheet under each other, the columns are not ALL in the same order, some are, but some are not + there are columns in work sheet 2 & 3 that may not be in worksheet 1 at all.

Therefore, if you can imagine the above, I want excel to add the columns on the end of the table IF it does not exist already. IF the columns exist, it is to be added at the bottom of that column

I have been doing this the long way, aka manually, it takes hours.

Thats only like 1/16 of the full process and I have already discovered very powerful formulas for other areas, but this is just tricky.

Is there any genius out there willing to provide some advice??? Thank You