Sort receipts based on their dates - Problem with a nested function.

Hello Excel Forum!

This is officially my first post in this forum, so I hope I'm not making a fool out of myself, and I obviously hope that you can help me! - I am usually not a person who asks for help, since I prefer to figure things out by myself. But! After a whole day searching the internet for answers, I find myself defeated, and this is my way of accepting it. - Anyhow! Let me introduce you to my problem.

I am currently working with 2 sheets in Excel 2007, but I made a similar model on Google Docs, so that my roommates can see it as well - You can all see it here http://goo.gl/wzYuzU

1. "KvitteringerSeptember" With my two roommates and my receipts.
2. "Fordeling" All the food products named on the receipts sorted by date.

We have more than just food on the receipts, so we have to copy + paste our food into my first sheet.
But as we copy it onto the first sheet, I want to see which date of the receipts it belongs to, with the following function:

=if(B3=KvitteringerSeptember!$A$6=true,KvitteringerSeptember!$A$2,

B3 = CopyPasted food in my 1st sheet
A6 = Name of the food from my 2nd sheet
A2 = The date of the receipt of which the food have been bought.

Since I have multiple receipts, then I'm going to have multiple dates, which I solved by adding more functions to my function (Nested function)

=if(B2=KvitteringerSeptember!$A$6=true,KvitteringerSeptember!$A$2,if(B2=KvitteringerSeptember!$C$6=true,KvitteringerSeptember!$C$2,if(B2=KvitteringerSeptember!$E$6=true,KvitteringerSeptember!$E$2...
And until the end... f(B8=KvitteringerSeptember!$Y$6=true,KvitteringerSeptember!$Y$2,A7)))))))))))))

This method isn't that efficient as you might see.

1. I can only add the first food product of the receipts (As you can see in the code)
1.1 Which is why I have the final [Value_if_false] to A7, as in the previous date.
2.I have to write another IF function for each new receipt, which is rather confusing.
3. If it compares a product from the first receipt with an old product, then it's obviously going to return with the date of the first product.
- Which I was trying to avoid by adding the function [Greater than or equal to] before every date, so that the previous receipts dates would be lesser than the actual receipt it is comparing it to. (Without luck though!)

Anyone who have any ideas how to optimize these functions?
- Share a guide for a better way to sort this out?
- Or at least implement my [Greater than or equal to] function into my nested function?

Looking forward to hear from you, thanks for reading!
- Sincerely GubiiTheFish