If I were doing this with a client, I would make a table of records numbered from say 1 to 1000. Call this Serial Source. Then I'd make a formula URL button to set a value on a focus record with the values needed to create the child records and then look those up down to the Serial Source table and then execute a saved table to table import.
This would be all in one click. It's too much explanation to provide all the code if you have not done URL formula buttons before, so I'd probably need to have you book an hour or so with me to get this working.