There are 2 levels of edit rights you can grant users on a hierarchical process map. You can invite them to be editors in a map in general, but you can also choose which diagrams specifically they are able to edit.

There are 3 steps to managing editor rights in a Space. To have edit rights in a Space, the user must have been granted editor rights at the space level. Once a user has edit rights on a Space, they can then be assigned specific edit rights to a Map. 

Once assigned to a Map, all the Map editors are available to be granted edit rights to each individual diagram in the Map. 

You can set edit rights for each diagram in the map and control which editors can edit which part of your map. By default, all diagrams are set to be editable by all map editors.

Open the map management app. You can do it either from the map list:

or from the diagram editor:

Then select the "Edit rights" tab in the right sidebar.

By default all map editors can edit any draft diagram. This is because on the top level diagram the toggle "All map editors" is turned on and all child diagrams have a setting "Inherits right from parent" turned on by default as well.

If, however, you would like to restrict some editors from being able to change a particular diagram, simply switch the toggle "all map editors" to off on the top level diagram, or the "Inherits right from parent" toggle on any child diagram. You will see the DENY button next to each editor's name, allowing you to restrict particular editors from editing this diagram.
​

You can always reverse this action, either by switching the toggle "All Map editors" to "on", or by clicking the ALLOW button against the denied editors. 

Using the inheritance settings you can quickly customize who can edit which parts of your process map without having to set it up on each diagram separately.