Hi,
I don't understand what you mean by this. This number range is not external, but internal one. You can set the current number, of course, though I don't understand why would you do such a thing. Only if you have transported number range and numbers were messed up.
In any case, you can set number range in OF19. Then, while creating FM document, which is relevant for update of FMIFIIT table, the entry in this last would obtain a number. You should not expect, though, the strict sequence as the documents could be created with gaps, if the buffer setting in the technical properties of the table are switched on.
Regards,
Eli