In the Workbase graphical interface it is possible to create Entities, Attributes and Relationships, indicating their attributes (has) and their roles (plays). Once created it is possible to add or modify the attributes, but I did not find where to add or modify the roles in this graphical interface.
Thanks for your suggestion. That feature is in the roadmap and will be implemented.
Also feel free to make pull requests to the repo directly if you’re interested.
I appreciate your prompt response. In the meantime I do not know if you can tell me how I can add a role to an existing entity using graql (command line).
You can simply define the role that a concept is allowed to play:
define siblings sub relationship, relates sibling; define person sub entity, plays sibling; commit