Either you want to update a record or append a record. Either way a query should be used. Maybe you could create an append query that links the estimate to the quote and produces the association in a table if one does not already exist. Or when producing the quote, use an append query to write a record of the quote and estimate IDs to a table.
To create a dynamic append query, first create the append query using the query builder and sample numbers. Then switch to SQL view so you can copy the code. Then set the sql statement to a string, but replace the sample numbers with the variables with the new IDs. Then use the currentdb.execute command to run the query and add the records.
I can discuss the other method of linking Estimates to Quotes and appending only the records that do not have association if you think that would be a better method. There must be a key to connect the two tables to ensure not duplicating associations. Just repost and ask. But be sure to document the key that can be used for the process.