KKL forests which are not

In the very useful data we got from KKL there are occasional patches that, on the ground, and based on satellite images, are not forested. This is KKL managed land that is often what we tag heath (בתה או גריגה).
An example is “יער מודיעין” just west of the city (BTW, how do I link a feature here?)
Now these areas are complex multipolygon relations with inner and outer boundaries, tagged under “managed forest”. How do I change them to reflect reality without deleting or overriding the data?

To link to a feature, if you know the number of the feature:

To get the number of the feature, you can examine it in JOSM/Potlatch

There is no need to delete a relation, or any OSM entity, in order to update them. In fact, it is better to modify entities and keep their history than to replace them.
To modify a relation, it is easier to access it through one of its member ways.

For example, open the Modi’in Forest relationship - http://www.openstreetmap.org/browse/relation/1638370

  1. Pick any of its way, say http://www.openstreetmap.org/browse/way/119077660
  2. You’ll find an “Edit way” link below the map. It will open Potlatch at the center of the way (area).
  3. Once you’ve selected the appropriate way move to “Advanced” mode (at the bottom) and you should see all the relations it belongs to in the bottom table.
  4. Double-click on the appropriate relation (avoiding the “role” field) and a the relation window will show
  5. Scroll the window down and click on the “Advanced” link
  6. The advanced view allows you to add, delete of modify all the tags of the relationship.

Note that properties like “Managed Forest” apply to all areas of the forest.

If a forest is combined of different types, I would consider tagging each area/way individually, and leaving the relationship as holding place for the name and any other property that is common to all areas/ways.