typically, you'd use a

DELETE

operation in

WriteRelationships

to remove the previous relationship and

CREATE

to add the new one, in a single call

ok, but it means I need to have smth like this in updates array

[{
    operation: v1.RelationshipUpdate_Operation.DELETE,
    relationship: {
      resource: folderObjectReference,
      subject: employeeSubjectReference,
      relation: 'manager',
    },
  },
  {
    operation: v1.RelationshipUpdate_Operation.TOUCH,
    relationship: {
      resource: folderObjectReference,
      subject: employeeSubjectReference,
      relation: 'viewer',
    },
  }
]

so I need to check current relation (manager) anyway, or should I have delete operation for all of the remaining relations: manager, editor, blocked (except the new one: viewer)?

Generally you’d check but you can just add the others