The records which are exported should be mark as "Tag for export" in sandbox.
Thanks for the feedbacks.
In our business case, we are not starting from scratch.
We wanted to review first in a Full Sandbox impacts categorys changes: New / Disable Categories / Change Labels / Change parent.
The ideal scenario we imagine is :
1. Dataloader upload into FULL
2. Analyse impacts on existing incidents (Opened / Closed)
3. Upload or deploy into Prod
We are talking about 500 Categories.
Manual management focusing only on Changes (about 200) is maybe more simple as it allows graphic checks on tree hierarchy and reduce time to create a "loadable" file