Block serial nos. (scrap) vs. Output

Mula

Hi all,

i am asking for your help with a "little" problem of mine.

i need to create serial nos. for traceability items in advance, when releasing an production order.
After creation, we print barcodes and attach those labels to the item during the manufacturing process.
This means, the once created serial nos. may not be deleted or reused for other items.

Currently, I am creating serial nos. automatically by calling the built-in functions as Reservation entries (T337)
also i do create entries in Table 6504 (serial no. informaton) automatically for each reservation entry.
Manual deletions or modifications in T6504 are not allowed.
This way i am able to check if there is a double serial no. (e.g. when someone is resetting the no.series).

Also, the serial no. could end as scrap. Users want to flag the serial no. as "blocked" in the serial no. information card.
And that's where my problem starts now...

Let's say we want to produce 10 items and therefore generate 10 serial nos. in advance as reservation entries.
and use the standard production journal for posting.

Then we end up with one item being scrap, so we need to post an output of 9 and scrap 1.
Changing the qty. will need a regulation of serial nos. in advance...

How can i adjust the item reservations without deleting the blocked serial nos.? they should not get posted of course, but
may not be deleted.