"Add all" button for categories in the batch interface where there are fewer than x members of the category

[RichardTaylor]

As for what "x" should be:

• There's little point having an "Add all" button if there are more members of the category than the cap on number of authorities in a batch.
• x could be set to to the level of the cap on the number of authorities in a batch.
• x could be set at 333 (the number of principal councils in England), or 398 (the number of principal councils in the UK).

x could vary depending on how trusted the user is.

[WilliamWDTK]

One could also have a lower limit for a point at which there is little benefit to an "add all" button, and the benefit of the user (perhaps more consciously) reviewing which authorities are added is greater…