I have a form where a part number, qty received, and serial number are entered,
and I generate a request number.
(other information is entered as well, such as name, address, etc.) So it is
one record per request number, easily done and no problems.

Now I am told that for each request number, there could be multple part
numbers and each part number may or may not have a serial number.

I was thinking of splitting up the form and enter the name, etc. first, then
when they submit, it inputs into a table then use cflocation to go to another
screen, passing the reqeust nubmer, to enter the part number, qty, and serial
number. If they check a box to indicate serial number, then I would like to
autogenerate that many serial number entry lines based on the qty entered.

Is there a better and more efficieint way to do this ? The part numbers and
serial number are in a separate table so the part number will repeat but the
serial numbers will be different.

Thanks for any help or advice.

Sounds like a shopping cart. I wouldn't store any data into a db or generate
an order number until the user has indicated that he has finished entering data.

You will probably have to take a good look at your database as well. You need
a one to many relationship somewhere.