Finding and inserting value from previous list.

First off a disclaimer. I have also posted this same question on a different forum but after three days I haven't received a reply yet so I thought I would branch out. My previous post is at http://www.mrexcel.com/forum/excel-q...ious-list.html Please feel free to post a reply on either forum and I will be sure to update both as solved when it is.

I appreciate in advance your help. I will try to give as much information and background as I can.

The basis of my needs is to be able to find in a list of names, a duplicate name from previous list and then grab and populate a number from that row. Here is an example
A B C D
Doe,Jane $1000 $250 $750
Smith,John $700 $100 $600
Wilson,Alan $1500 $1500 $0

I update the list, some names are added and others taken away. When I add the new list, column C of every name is $0. I want the formula to find names from the previous list and populate Column C with the value of Column C + D of the corresponding name. Also I have a separate formula that simply is D=(B-C) The result of what I would want this to look like is this...
A B C D
Doe,Jane $1200 $1000 $200
Doe,John $500 $0 $500
Smith,John $1000 $700 $300

As you can see there was a new name added to the list (Doe,John) and a name taken away from the list (Wilson,Alan). Column C is the only Column that I am wanting to auto populate. The Value in Column B is a variable that is managed by another program so you don't have to worry about that.
Keep in mind there will be multiple instances of this list and the same name will occur more than once in the spreadsheet. There are not duplicate names that are different customers though as my other program takes care of that. eg. "Doe,John" and "Doe,John #2". I only want it to grab the information from the previous list not ones previous to that list(if that makes sense) third example...
A B C D
Doe,Jane $1500 $1200 $300
Doe,John $500 $500 $0
Miller,Joe $700 $0 $700
Smith, John $1300 $1000 $300

My current method of accomplishing this is to select the previous list and print it. I then go down the new list and cross reference it with the old one keying in the values by hand. This would be a huge time saver as the list is 250 names and growing. I hope I have given enough information but undoubtedly I have not. So feel free to ask me any questions and for more details. I did not want to go to in depth for fear of my post being to long.