Hello,
Denodo can create associations automatically for JDBC base views by clicking on the discover associations option.However, In case of derived views associations are not propagated from base views to derived views. Similarly, in your case since the associations were created in the base views, so it will not be inherited by the derived views and hence you have to create them manually.
You can refer to associations(https://community.denodo.com/docs/html/browse/6.0/vdp/administration/restful_architecture/associations/creating_anassociation) section of vdp admin guide for more information.
Hope this helps !