I understand in version 15 functionality was added to allow to create a publication for all tables within a schema. How would I need to do this in v12?
If it's a newly added feature in v15 there isn't a way to do the exact same thing in v12. In v12 you can get auto-add and wildcard on the full database only. If you need a subset, schema-based or otherwise, you need to list every entry and you will not have an auto-add behavior.
The documentation for 12 does not show schema.table just table names
Anywhere you can write a table name should be able to accept the full, schema-qualified, name even when it isn't called out explicitly.
