Adding customer # to file for Contribution Import Utility for text-to-give results from GiveLively export

Hello - orgs that are using the Contribution Import Utility for third-party gift data, how are you looking up and adding the customer id# to the file before import? Or are you importing as new accounts and relying on the merge procedure to clean up later?

I'm working with our Record team, testing with GiveLively export data, which includes email address and phone number in addition to the contribution data - I gave them SQL queries to return phone, email and customer# so they could do a VLOOKUP to pull the customer# into the file before import. Seems clunky.

Does anyone using this utility have a better process?

Thanks in advance!