From the processing point of view, when you change the URL, Pi-hole sees a completely new list.
Everything related to the old URL will change. Gravity update will overwrite the old list contents anyway, so there is zero gain compared to create a new entry.
From the group management point of view:
If you want to change the URL for different lists, with different comments and different group assignment, you would need to change them manually, one by one, even if there was a way to do it via web interface.
On the other hand, if you want to replace the URL for just one list (or for multiple lists with the same comment and assigned to the same groups), the job is easy:
- type the new URL (or multiple URLs, separated by spaces);
- type the comment (the comment will be the same for every list);
- select all groups (selected groups will be assigned to all lists);
- Click on the button to add them.
