To add a single relation to a namespace in Ory Permissions, you need to define the relation within the corresponding class in the Ory Permission Language (OPL). Ory Permissions only has many-to-many relationships between objects and subjects. To reflect this in OPL, pluralize the relation name, for example,

viewers

instead of

viewer

. Here's an example of how to add a

viewers

relation to the

Document

namespace:

typescript import { Namespace, Context } from "@ory/keto-namespace-types"  class User implements Namespace {}  class Document implements Namespace {   related: {     owners: User[]     editors: User[]     viewers: User[] // Add the viewers relation here     parents: Folder[]   } }  class Folder implements Namespace {   related: {     owners: User[]     editors: User[]     viewers: User[]     parents: Folder[]   } }

Source: [Create a permission model](https://www.ory.sh/docs/keto/modeling/create-permission-model)

In Ory Permissions, only many-to-many relationships are supported between objects and subjects. However, you can model your relationships in a way that simulates a one-to-many relationship, but keep in mind that the underlying structure is still many-to-many. Source: [Create a permission model](https://www.ory.sh/docs/keto/modeling/create-permission-model)