Use Append Query.
Here is how to do it:
Let's say, you have two tables, tblMain, which is the first table, and
tblSecond, which contains the records you need to append to the first table.
So, open the Queries object, and create new Query in Design View. In the
Show Table dialog, select tblSecond and click Add. Close the window.
Then change the Query to Append. In the Append to select tblMain.
Drag all fields from tblSecond to the lower pane, except the Primary Key.
Then click the ! sign to run the Query.
Answer Yes to the question.
You are ready. You have append the fields, and the Autonumber is generated
by Access. You don't need to worry about it.

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Marin Kostov
Microsoft Office XP Master Instructor