There is no such type of reference in Vertabelo. Please notice that Vertabelo works on physical database model. ISA reference is usually related to conceptual database modeling.

To model inheritance in your database you can use plain references with techniques described here:

http://stackoverflow.com/questions/190296/how-do-you-effectively-model-inheritance-in-a-database

http://stackoverflow.com/questions/386652/techniques-for-database-inheritance

Thank you for asking this. Currently Redshift support isn't on our roadmap.

However Redshift is based on Postgres so you should be able to work without direct Redshift support. We covered this topic here:

http://support.vertabelo.com/topic/573926-how-to-import-a-db-schema-from-redshift/

I remain the idea opened so other users can upvote it.