Order Upload to clean up a list for segmentation

Hello!

Currently I am slowly working on a project to help out the development side of our organization, and I might be over complicating the process.  I'm 3 months in to learning Tessitura, so please chime in if you think there is an easier way to achieve what we're looking for.

We have been given a list by a consulting firm that is analyzing our data regarding customers that could potentially be bumped up to higher donor levels and ticket buyers.  That list is something that IDEALLY we would upload into list manager, and "slice and dice" that way for mailings and analysis.  Our problem is that it is using old and current data, and the customer numbers don't match up.  So when I upload, Tessitura only looks at the constituent ID, which may or not be correct, and spits out a name.  So my small list of 200 names ends up with about 100 wrong names coming back on the uploaded list.  (In a perfect world, I'd just slowly fix the small list and be done, but there is another list where the same project has to be done, with well over 1000 names.)

Digging through the info on Tessitura, the answer that seems most helpful to to create an event and use "order upload manager" to upload those names into the event, since it will clean up the constituent ID's as well as incorrect addresses, phone numbers, etc.  I have been stopped in this process by also needing to create the XML code that is needed to tell Tessitura how to upload the spreadsheet made.  It's above my skill level.

Any ideas or alternative ways to tackle the project?