I need help merging some data...

I have a scenario...

100,000 records in a SQL db has to be filtered and sent out to a vendor (column containing a sequential number will be used as key). There will be a total of 9 columns on the original record set containing NAME, ADDR, PHONE NUMBER, KEY FIELD, and so on... A filter would be applied to eliminate redundant addresses and phone numbers. Thus, the output will be around 70,000 records. This record will then be sent over and filtered by another company. Once the records have been verified, I will receive another file containing verified information only (estimated to be around 50% of the filtered records...about 35,000).

My problem will be when the 35,000 comes back, how do I merge this data with the original 100,000 from the original record set AND propagate the changes through to all of the records contained in the original file.

Any help would be appreciated... Thanks in advanced for your replys...