If you have old data where the item numbers were 2 or 3 digits long and you are stuck adding new ones in the logical order, it is possible to add a "0" to all the numbers in order to get more flexibility.
Go to Data Diagnostic - Tools - Renaming tools - Add a "0" to all items numbers :
When choosing the option, there is one precaution to take: MAKE A BACKUP to keep an old version. Once the changes are made, there is no way to go back.
When it is done, accept to continue.
Let the program make the changes until the end:
The program will renumber the items wherever they are found, including in the closed months.
The usual documents, pay slip, accounting document, salary certificate, etc... will be adapted by the way.